ASUS ZenFone 4 review – the littlest ZenFone has plenty to shout about

With thanks to ASUS for the handset. 

After reviewing the monolithic ZenFone 6 last week, its 4-inch little brother feels a lot like ‘honey, I shrunk the phone.’ It includes many of the same features as its stablemates, but at a miniature size and price. So what can ASUS offer for your £99?

The handset

First things first: this looks like a budget handset. It’s bound to, really. As the baby of the ZenFone family, it’s got the smallest screen (4 inches) and, like most babies, it’s pretty chubby. The back panel is matt plastic, designed to feel like ceramic. Which it kind of does, apart from not feeling cold enough. It’s hardened to be impact-resistant and comes in black, white, red, yellow and a bright turquoise blue – plus points for that. The back of the phone nestles nicely in your hand and there’s not too much slip, so you don’t feel like you’re going to drop it (I’m far too aware of this after the Huawei Ascend P7).

ASUS ZenFone 4

You might drop it when you try and get the back panel off, though. I certainly did, more than once. That’s because it’s unbelievably hard to remove, despite having a little indent to help you out. I had to resort to jimmying it open – not ideal. But with the SIM and microSD slots hiding in there, I didn’t have much choice.

I’d have preferred a uniform thickness rather than the thin sides and bulging belly ASUS have gone for: the phone looks like it’s floating when you set it down on its back.

ASUS ZenFone 4

It’s odd that this handset feels weighty when it’s only 115g, but I think that’s down to how thin and small it looks on first glance when there’s actually a fair heft at the back.

ASUS ZenFone 4

The front is pretty generic, with a gloss black finish on the bezels and ASUS’s signature concentric circles rendered in plastic under the screen. The circle design isn’t very noticeable on this handset, which seems a shame next to the ZenFone 6’s more obvious version – but then again, we’re dealing with limited space and money here. The ASUS branding is low-key, with just a silver wordmark on the front and back.

The volume rocker and power key are on the right, as with the other ZenFones – but bafflingly, they’re swapped around on the 4. The ZenFone 6 has volume above battery, and the 4 has vice versa. I think the 4 has it the right way round: it’s easier to hit the screen button first time when it’s at the top. The charging port is somewhat annoyingly placed on the top left side of the phone, but the headphone jack is sensibly located up top.

There are three capacitive (soft) keys below the screen, which is another plus point: they could easily have been replaced by software buttons in a phone as low-priced as this. There’s no backlight on them, as you’d expect, but haptic (touch) feedback is strong and noisy: repeatedly tapping the home key sounds like trying to start a lawnmower! You have to tap it quite hard, too.

The speaker sits on the back beside the camera lens, which means it’s very muffled if you have the phone face-up. It doesn’t go as loud as other phones, but is plenty loud enough for personal music and speakerphone calls. Music sounds noisy at higher volumes and the bundled headphones are unsurprisingly leaky, so music lovers will want to plug in some higher-end speakers or ‘phones.

The experience

The ASUS ZenFone 4 has just received an update from Android Jelly Bean to KitKat. That’s great at £100, although it does still have the love/hate ASUS ZenUI over the top. Which means a split notifications bar (pull down from left for notifications, right for settings), some preinstalled nonsense like Omlet Chat, and homescreen features that are handy if you can be bothered to customise them. It’s not bad, but as with many manufacturer overlays, it doesn’t improve on the stock Android experience.

As usual with ASUS, there’s an Intel processor (a dual-core 1.2 GHz Atom Z2520 with hyperthreading) and a thoroughly generous 8GB of internal storage. You can boost that up by 64GB with the microSD slot, too. Compared with similar-priced phones, the ZenFone 4 has more internal storage than the 4GB Moto E and Alcatel OneTouch Pop S3, but an inferior processor to the EE Kestrel and Pop S3’s quad-core Snapdragon 400. All four phones come with 1GB of RAM.

Over my week of using the phone, I did experience some lag with the ZenFone 4, but nothing terrible. The keyboard fell behind typing a couple of times, apps often took a little longer than you’d like to open, and the phone hung and got confused once or twice when multitasking. Gaming was a similar story: Minecraft, Machinarium and The Sims all ran beautifully for the most part, with only a couple of issues. That’s very good for £100.

The handset gets fairly toasty during any kind of gameplay or intensive activity, though. I appreciated it when playing games at a wintry bus stop, less so the rest of the time.

The screen

As with the Moto E, ASUS have found money in their slimline budget to put Gorilla Glass 3 on the ZenFone 4’s display. That’s more than you’d expect from a phone this price, and means you don’t have to worry much about dropping or scratching the handset. It’s not foolproof, but means it’ll be tougher than most sub-£100 phones.

ASUS ZenFone 4

At 4 inches, the screen feels a bit too small next to most phones, especially where typing’s concerned. I almost resorted to ordering Homer Simpson’s Dialling Wand at one point, because the tiny tiny keyboard made me feel like I had sausage fingers. For reading, apps and movies, it’s OK, but you do notice the lack of screen space quite often when navigation menus are cramped up or take half the screen.

The display itself has a good top brightness (although no auto-brightness setting, so you’ll have to adjust it yourself when you go outdoors), and comes with the ASUS Splendid app for tweaking colours. You can fiddle with colour temperature, hue, saturation, and toggle ‘vivid mode,’ which looks better on than off.

ASUS ZenFone 4

It’s not the sharpest screen in the world, having only WVGA resolution (800×480), giving it a pixel density of 233 per inch. That’s identical to the £80 Alcatel OneTouch Pop S3 and £39 Vodafone Smart 4 Mini, but the ZenFone’s screen appears clearer and much less smudgy than the Alcatel’s. It’s not going to blow you away, but you won’t be noticing pixels all the time either.

Games, movies and pictures look good for the most part, as long as you’re looking at the phone straight-on. Tilt it certain ways and suddenly it’s useless, as I’ve demonstrated in the video review:

Comparatively, this isn’t a great screen for the price. The identically-priced EE Kestrel has a quarter-HD screen (245ppi), and the one-fifth-cheaper Moto E manages 256ppi. It’s easy to understand why it’s this way: no budget phone is going to be good at everything (though the Moto E comes close), and ASUS have chosen to put their money into hardware instead.

The camera

The ZenFone 4’s main camera is a 5MP snapper that can also record HD video at 1080p. In good lighting, you’ll get a clear, colourful shot that’s easily good enough to share online:

ASUS ZenFone 4


Results do vary though, with lower-light environments sometimes faring badly (especially without a flash) and bright colours occasionally coming out overexposed.

The modes really do make a difference to picture quality, which is good to see: these two sets of photos were taken with and without HDR in gloomy lighting. Without HDR, the building shot looks like a painting, which is quite cool but not what I wanted.

Taken on an ASUS ZenFone 4
Without HDR
Taken on an ASUS ZenFone 4
With HDR
Taken on an ASUS ZenFone 4
Without HDR
Taken on an ASUS ZenFone 4
With HDR

Unlike the Smart 4 and Alcatel OneTouch Pop S3 cameras, I was relieved to see the ZenFone 4 camera isn’t fixed focus. It’s actually got a pretty quick autofocus and the manual one’s not bad, although it struggles more in close-ups.

ASUS ZenFone 4

It’s not a particularly speedy snapper: the image stays on the screen for well over a second after you’ve taken it. I thought this might be a review window, but the settings menu claimed that ‘review duration’ was set to Off, so I guess it’s just a sluggish camera. Helpfully, you can do a burst of photos by holding down either side of the volume rocker, which is much faster and helps you capture that all-important shot when your subject is moving quickly.

It’s great to see that the ZenFone 4 comes with the same excellent software features as the other phones in the ZenFone range. Resembling the Sony Xperia Z2’s camera menu (although slightly less exhaustive), functions include Miniature mode (tilt-shift), depth of field, All Smiles (takes several photos so you can choose the best facial expression for everyone), Time Rewind (captures before and after a photo so you can find the best moment), and the utterly fantastic GIF mode that lets you make an animated gif instead of a video. It works really well and will have strong appeal for the Twitter and Tumblr crowds. The only downside is that you have to remember to activate the mode first – it doesn’t work retroactively.

Taken on an ASUS ZenFone 4
This gif makes me need a wee

This is a bigger issue on modes like Smart Remove, which takes out annoying passers-by who thoughtlessly wander into the frame of your photo. But how often do you notice a photobomber before you take the picture? Usually it’s only afterwards that you wish they’d got out of the way, and that’s no use with these functions.

The Depth of Field mode is a bit hit-and-miss, but when it works well, makes your photos look like they were taken on something that cost a lot more than £100:

Taken on an ASUS ZenFone 4


It’s also worth transferring photos onto a different screen before you judge them: this pillar box shot had ridiculously high contrast on the ZenFone’s screen (although I did have Vivid Mode on), but looks much better transferred to a PC.

Taken on an ASUS ZenFone 4

It’s HDR equivalent sorts out the overexposure on the buildings behind, but loses a lot of the brightness:

Taken on an ASUS ZenFone 4

Neither truly captures the scene, but reds are often an issue on lower-cost cameras.

There’s no flash on the ZenFone 4, although it does have a front-facing (selfie) camera. As with the OneTouch Pop S3, I’m not sure it was worth including. It’s 0.3MP and takes grainy photos that you’re probably not going to use. I’d have preferred a flash.

Taken on an ASUS ZenFone 4
The battery

The ASUS website lists the ZenFone 4 battery sizes at 1200 and 1600mAh, although the one I had is 1540. That’s low even for a budget phone: the Alcatel OneTouch Pop S3 and EE Kestrel both pack 2000 and the Moto E has 1980.

Curiously, though, it performed better in our standard battery test than the Pop S3 and the Kestrel: after two hours streaming a fullscreen film over Wi-Fi with GPS enabled and screen brightness set to max, the battery depleted from 100% to 52%. The Kestrel had 50%, the Pop S3 48%. So despite having less juice to work with, the ZenFone manages it well.

That’s not to say it’s a workhorse: it was dead or dying by bedtime every day. And that’s with fairly low use: I didn’t make many calls or stream much, so a heavy user might well find this phone tricky.

That said, there’s a profusion of power saving features on the ZenFone 4, some of which were auto-enabled before I even set it up. For instance, at first it would only download its system update (to KitKat) when the screen was on – I was baffled to come back and find only 20% progress in an hour until I realised what was going on. There’s an Ultra-Saving mode, which automatically disconnects from data when you’re not using the phone, and an Optimised Mode for less drastic power-saving. You can also set up a Customised Mode of your own, deciding which tasks should be allowed to use data and what screen brightness level to associate with them. That’s pretty useful if Optimised Mode doesn’t suit your preferences.

ASUS ZenFone 4


Keeping the screen brightness turned down helps a lot with staying powered-up, but since the ZenFone 4 doesn’t have automatic brightness adjustment, I found myself lazily leaving it on max and then cursing myself later when my battery ran out. It also bugged me that opening the camera app would pop up a message asking if I’d like to close the camera app because my battery was low. I just opened it! You’ve just wasted more battery asking me that! Argh.

Big plus point though: the battery is removable, so you can always swap it out.

The lowdown

For £99, this phone goes a long way to being brilliant. I’m not a fan of how thick it is, but in one of the more interesting colour options, it looks appealing. Performance is very, very good for the price, and the inclusion of Gorilla Glass, 8GB storage and all those camera modes is fantastic. The downsides are mostly in the screen resolution and viewing angles, the poor selfie camera, and to some extent the battery. But they’re not major issues by any stretch.

Whether you spend your ton on this phone will come down to your priorities. If screen resolution is important to you, you’d be better off with the Moto E or EE Kestrel. The Kestrel also has 4G, which the ZenFone 4 doesn’t offer, but its camera and internal storage aren’t as good, and it looks dull. You also have to deal with the Huawei Emotion UI on the Kestrel – ZenUI is much better.

If you’ve got £100 to spend and you’re all about the photos, get this one. Just don’t blame us when you spend all your time making GIFs with it.

Thumbs up

Excellent camera features
Comes with KitKat
Generous internal storage

Thumbs down

No 4G
Useless selfie cam
Narrow viewing angles


EE Kestrel
Alcatel OneTouch Pop S3
Motorola Moto E

Holly Brockwell

Comments are closed.