Just received my new Paperwhite at the end of last week, and it took me two days to get used to it. Some initial thoughts:
--I really liked how the Kindle Keyboard managed collections. When sorting by collections, they sorted by most recently accessed collection on the main screen. I've had to make the move away from collections with the PW and I didn't like that at first. It sorts collections alphabetically. No worries, just not a big fan of this.
--The light's incredible. I thought setting it to zero = turning it off. There's still a bit of light at zero, and I think that's fine. Very bright, very even, very clean. I tend to read at 24 in full light, and 6 in no light. I tried reading at 0 in full light, but the clarity is just so nice at 24 that I can't go back easily.
--The touch screen took some getting used to, but I love the touch-screen keyboard. Very smooth, a bit slow (e-ink, after all), but very good.
--I love the size, and I have it in the new cover, and it's a perfect combo.
TL;DR: I like the PW a lot; I don't like the change to the collection sorting method.