I don't have the Sony 650 but the 350. The 350 is perfect for me. The major differences is that the 650 has a little bigger screen, SD card slot & I believe can play MP3 & audio books? I'm not positive but may be worth checking out if it is important to you. The 350 is easy take take everywhere even with a cover on it (I put a band around my cover to keep it from opening if is should be dropped)
I'm sure you will be hearing from the Bookeen people. They love theirs like we love our Sonys
