The e-ink devices are nice in that they only use power when you're turning the page, not while you're staring at it. And they're a bit easier on the eyes, I think, than a colour LCD screen. I still use my Kindle for reading books, even though I have a tablet and could read them there. Mind you, the tablet isn't a bad reading experience, either, but it doesn't have the battery life of the Kindle.

The iPad mini I have isn't much bigger than my Kindle (and a bit thinner). I can carry it in my purse as easily as the Kindle (and sometimes both of them together, but it has a colour screen so I can see pictures and such on it. I also can draw on it, which was a use case I never even imagined when I got it, so you'll likely find other things to do with a tablet besides reading.