A bunch of us from the Amazon forums had a meetup at the Starbuck's in Santanna Row in San Jose Saturday to compare Kindle screens and discuss contrast issues and so on.
All in all, we had 10 Kindles (and 1 OLPC). 7 Kindle 2s and 3 Kindle 1s.
All of the Kindle 2s looked pretty much the same at the same font size.
The Kindle 1s had noticeably darker text, but most of us were happy with our Kindle 2s. If you are used to the Kindle 1 and you read your books on the smallest font, then I can see how a Kindle 2 may not be acceptable to you.
2 of the Kindle 2s exhibited the "wash-out" bug when you turn pages in direct sunlight and will be replaced.
We had several people come up and ask us to show them the Kindle and they seemed very enthusiastic. Maybe made some sales!
John Serafin took some pictures of the Kindles for comparison: