Full disclaimer: I've just moved house, and the thought of a house without internet fills me with The Horror, so when Virgin offered me one of their fancy new USB dongles to review, I jumped on it. And it seems I'm not the only one - fixed line broadband connections are dropping in the UK, perhaps in favour of the increased flexibility of being about to connect over the HSDPA network.
Dongles are great, as long as you're not a heavy hitter when it comes to downloading films or TV programmes. If you think you might want access to the internet away from the range of your home, i.e. a coffee shop, a conference etc, they're certainly worth considering.
Plug in the Virgin USB stick, and it auto plays the connection software you need. I actually had to run this a couple of times to make it stick, but once you're installed it, it's just a case of hitting 'Connect' in the programme.
The dongle will display one of a number of different coloured LEDs, so you know at a glance whether you're connected to the GPRS, 3G or HSDPA network. I live pretty far North in London, where 3G can be sketchy, but I got an HSDPA connection most of the time.
It wasn't perfect - occasionally I'd have to disconnect and then reconnect to regain the faster connection. But I used it for a full day of working from home and this only happened three or four times.
As far as the usage is concerned, they tie you into a lengthy 18 month contract, for £15 a month. That £15 a month bags you 3GB of data, which they equate to 2000 emails, 100 hours of web surfing, 200 music tracks and 100 two minute videos. The modem itself is free. If you're unsure on whether this will do you, the Virgin site has a pretty handy calculator to estimate how much internet you suck up, as well as a coverage map.
Overall, it wouldn't suit me to use something like this full time. I routinely receive massive image files, and I'm not a stranger to downloading entire TV series (legally, obv). But for someone that wants the flexibility to move about, or just can't be bothered to install a landline and a broadband connection, it's certainly worth a look.