For what it's worth, my 3G, which I got jut prior to the 2.0 firmware update, has had zero problems with the 2.0 software whatsoever. Of course, I also have almost no non-default apps on there short of the MySpace, Remote, and Pennies applications respectively.
Pennies, btw, is a bare bones, but nice little finance app for $3; it's from the same people responsible for AppZapper on OS X.
A quick search in the thread didn't yield much on screen protectors, but I may have been searching the wrong terms. Any consensus on how those fare?