I respectfully disagree with these conclusions. I've owned the 505, 300, 600, and 900 at one time or another. I find the advancements of the 900 to make it a much better reader than the 600. The screen on the 900 is easier on the eyes than the one on the 600. Since neither the 600 or 900 are pocket size, the extra wide screen on the 900 makes reading PDFs easier.

The Sony takes a lot flak over the cost of the 900, but it comes with an AC charger, a nice built in cover, removable battery, a case logic case, and a 3G radio. That is a good bargain for $100 more than the cost of the 600.

If I was to venture an educated guess, I would say that the 600 will be the first of the current Sony readers to be retired.