My fiance has the Nook and it is AWESOME!! i have used it, so easy to use. She has the one that has the E-ink. (not the newly released full touchscreen ones). IT has a small touchscreen at the bottom that works really well. I have used it and read numerous books on it and love it. Do get the 3G plus Wifi one, worth the money IMO. Also with the Nook, the books you have bought can be read online if you get a Nook app for your computer (free), your smartphone (free). The way it works is it links with your barnes and noble account. awesome stuff.
I recommend staying away from the sony ones and stuff. heard it can be difficult to get books and you have to hook it up via USB, so it sucks. I like the Nook because it is a product of an actual book store and you know they will have what you are looking for. Also Barnes and Noble has the "lend me" option that allows you to lend a book to a friend for two weeks.