I just recently purchased a kindle paperwhite and it is the most amazing thing I have ever owned. I love everything about it. I spent a lot of time wondering whether or not I should buy one since I already have one of the original nook ereaders. But I found myself being annoyed that I couldn't read in my room at night because it was too dim even with the light on. So I went ahead and made the purchase for the paperwhite and I have no regrets about it.
The lighting is really good. I've been reading at night in the middle settings and it' perfectly fine. I think my favorite feature of it is the option to see how much time you have remaining in a chapter or in the book. At first I thought it seemed like a useless feature, but I love being able to know whether or not I have enough time to finish a chapter before I go to bed. I just hate stopping in the middle of a chapter.
Unfortunately I do seem to be having the discoloration on the screen that a lot of people have complained about. It's not completely obvious at first, and I see it more in low lighting than I do in the middle of the day. But it's not bad enough that I feel like I need to return it. It looks like this is a problem that a lot of kindle users are having. I was hoping that since I waiting so long before purchasing it after the release that the problem would have been solved, but alas. I do still like it though.
Overall I'm incredibly happy with my purchase and I think it's a lot better than my nook. I've only had it for about a week and I have already read three books on it. That's amazing!