I picked up a new Sprint Treo 650 yesterday; it's a keeper. It is in all the ways I can find superior to my Sprint Treo 600.
* The keys are bigger, flatter and easier to push; it is much easier to type on the 650.
* The screen is SO much nicer; photos look great!
* The camera is totally useable, even in low light. The camera on the 600 was useless, IMHO.
* The screen resolution allows other apps to work better; for instance, PalmVNC looks much nicer and is much more useful as the higher resolution doubles the size of your control window. Also, pssh will allow unix apps that require minimum terminal sizes (such as "w") to funtion properly. You've never seen terminal text so small, however.
* Bluetooth is very cool. Setting up Bluetooth syncing is terribly easy with a Mac, and the syncing is very handy, if not faster than USB sync.
* Versamail 3.0 (only available on the 650) seems to have problems with my SSL IMAP server; I have been unable to use it so far. Sprint support is contacting Palmone about this problem; in the meantime the Snappermail Demo works fine.