No problems from a speed perspective. Never restored a backup to my phone. Also don't seem to have the same IMAP email issue noted above. What I really liked was that all my settings, apps, and pages were the same after the update. Nice job on Apple's part for the update. Made it very easy.
That said, the only trouble I have been experiencing is with iTunes. First, I couldn't sync notes. Posted a thread and got it resolved. My main issue is with the amount of time it takes. My 16gb phone is around 1/2 full and it has been taking 3-4 times as long to backup as it had previously. Seems to get stuck around 15-20% of the way through the backup and hangs. If it makes it past that, it hangs around 70% (just estimates based on the bar at the top).
EDITED: Original post made at 11:30 after I had already started to synchronize. It's now almost 12:30 and it finally finished.
Does anyone else experience such long sync times?