My favorite way to test any e-reader is to see if I still like using it when my reading material isn't exactly thrilling. For the past week, I've been using Amazon's newest Kindle to get through a book called Oh Crap! Potty Training and I still like reading on it more than any Kindle I've tried.
Thin; Weighs next to nothing without the cover; Feels great reading with one hand
Expensive; No adaptive backlight; Not waterproof