If you're simply running into sync problems...that is the iOS upgrade went okay but your iPad just won't finish syncing, that's not new to iOS 5. It's possible something about the upgrade is problematic, but iOS devices hanging on a sync has been around for years. It's usually due to corrupted files of some nature.
The easiest thing to do is to reset the iPad as well as close and reopen iTunes. That usually fixes things.
Reset the iPad: You can do this by pressing the Home button and the Sleep/wake button on the top the iPad's case and holding them down together for at least 10 seconds, until you see the Apple logo. The iPad should then reset itself. The boot up process will take longer than the restart. Try syncing again.
If that doesn't do it, try restoring from backup first.
Open iTunes > Preferences > Devices > Check "Prevent iPods, iPhones and iPads from syncing automatically".
Connect your iPad and in iTunes control-click or right-click on your iPad (listed in the left-hand menu). Click on "Restore from Backup".
After it's finished disconnect your iPad from the computer, shut down iTunes and then reconnect your iPad to your computer and try syncing again. If it still hangs, try deleting the backup and starting fresh.
Open iTunes > Preferences > Devices > Click on the device's backup in question and click on "Delete Backup" and confirm.
After that reconnect your iOS device to your computer and let iTunes create a new backup and sync.
If you're using iCloud to backup you can do the same thing but you'll need to turn the iCloud backup service off first.
On your iPad open the Settings App > iCloud > Storage and Backup > iCloud Backup "Off". In iTunes click on the "Back up to this computer" radio button.
Then perform the iTunes backup listed above. Once the backup and sync are done on iTunes you can turn the iCloud Backup service on again.
FWIW I'm using the iCloud Backup without any issues (iPad 1) but I also keep a random backup on iTunes the "old fashioned way" just in case one or the other goes wrong.
More here:
iTunes: About iOS backups
iPad: Unable to complete backup in iTunes
Hope that helps!