Upgrade on 8GB iPod Touch (my guinea pig device) went relatively well.
Started at about 10:30 PT, download-only in about 30 minutes, got the stupid 3200 error code when in update mode. Didn't see any help on the Apple site, restarted the update and it was done 30 or so minutes later.
I came to this site and see that the 3200 error is common and not a biggie.
The thing I found different was that at one point during the restore, the device appeared to be in sleep mode. iTunes said it was restoring but the screen was black. After 10 minutes, I woke up the iPod, and it took me through basic questions on the device (iCloud, locator, etc.) I thought iTunes was in a loop and almost disconnected until I saw more apps being added to the device. I waited it out and it finished. Brought up 3rd party apps and all appeared well.
Started the iPad update 30 minutes ago The download-only says it take 4 hours. Disconnected my iPad and will return later to update it.
Note: My iPod is using less than 4 GB and it took 30 minutes to restore it! My iPad is using 20GB of its 64 GB so it will take a while.