If you want an ebook reader and you have £70 or more to spend, you'll want to buy an Amazon Kindle. You'll be forever locked into buying books from Amazon's shop, but what a shop it is. The size and power of Amazon means that publishers have made available almost all of the titles you could want in digital form, and you can download meaty samples of the books before you decide whether to buy them or not.
If you're in this price bracket, your choices are now essentially narrowed to the basic Kindle for £69, or this £109 'Paperwhite' model with a higher-resolution screen and a screen light. If you can afford the extra, text on the Paperwhite screen looks better than on the normal Kindle, much more like a real book, although we're not yet at the stage where you can't tell the difference between the two.
Long battery life
As with previous models, the battery on the Paperwhite lasts forever -- a week or two for me, depending on how much I read. When you're used to charging a phone once or sometimes twice a day, that's as close to forever as we're going to get for a modern gadget.
This Paperwhite is actually an upgraded version of last year's very similar model -- it has a faster processor, which makes pages turn slightly faster, and a better light, which is brighter and more evenly lit across the screen. Neither of those things particularly matter and aren't reasons to upgrade from last year's Paperwhite if you own one, but they are nice to have.
A new light
Having a light on your Kindle isn't essential unless you read in the dark regularly, but it is a useful addition. It's easy to adjust the brightness of the light from the touchscreen controls, and Amazon says that having a strong light helps prevent screen glare when you're reading in the sun. I'd love to be able to test that claim, but the British winter makes it impossible. It works well in the dark though, although I found it irritating that you have to adjust it manually, rather than the light automatically compensating for its surroundings.
In addition to longer battery life, one of the reasons to read books on a Kindle rather than a tablet is the weight of the device. At 206g, it's well over 100g lighter than aor an , for example, so when I'm reading I find a Kindle much more comfortable.