One of the things I love about Tumblr compared to most other blogging platforms is the HUGE amount of choice when it comes to themes. Not only do you have access to thousands for free (obvs there are some paid ones too), but if you're handy with a bit of code you can customise them even more.
Tumblr is pretty versatile and can be used for long, wordy posts or just tiny quotes, but what the platform does really lend itself to is photographs and images, which is ideal if you're looking to start a photo blog or a portfolio. Obviously this is largely dependent on the quality of the images AND the theme you choose.
If you know Tumblr is going to be more photo scrap book for you than scribbly diary, then take a look at our seven favourite themes for photos, juicy fashion editorial, portfolios and making the most of big, lovely images.
The Scaffold Theme is probably my personal favourite as it's just so clean and simple. The boxes work well with images as well as text and they kind of hover over your blog. The fact they're all a little displaced makes it look much more interesting than a standard grid-like theme and the static sidebar makes your blog super easy to navigate. Available from Tumblr for $9.