Tried three units. Reading in the dark sucked on all of them. (Color blobs, light specks, uneven lighting.)
I am a VERY longtime e-book reader, including stuff like using old Palm Pilots, and the Sony PRS-700. I'm also a technology 'early adopter' and usually quite happy about it. With this context in mind, Paperwhite did not live up to the expectations created by Amazon.
I'm completely fine with other people being happy with theirs, though--their money can go to fund Amazon designing a better model for me later.