If you want to change your mind once more (I'm kinda sadistic), here are some really cool pictures of the Cybook, compared to a real book :
http://blog.lesenfantsdelo.com/tag/bookeen/
The article is in French, but you can still have a look at the pictures.
For info, a friend of mine took the pictures. He has been using the Cybook for a while and loves it. (for my part, I'm going for the iLiad, because of the big screen and the ability to write on it)
Please tell us your experience with the Sony once you get it ! I'm eager to see it