I tried restoring from iCloud backup after upgrading and it stalled out at 19 apps while restoring. So I wiped the device and tried again, same deal loaded up to 19 apps and stalled. I tried deleting some apps that I thought might've been giving it trouble and restarted a bunch of times but couldn't get it to move past that point.
I tried the old trick of going into Usage -> Manage Storage to try and give it a kick but no good. So finally, I gave in and wiped and set it up as a new phone. I don't think I've done a fresh install since like iOS 4, maybe that cruft contributed to my restore problem.
Unfortunately, doing this appears to wipe out the backup for this device immediately when I logged it in to iCloud. Beware of rely on cloud backups during the betas. (also that once you backup as iOS 9, you can't restore it on 8, but you probably already knew that)
I tried the old trick of going into Usage -> Manage Storage to try and give it a kick but no good. So finally, I gave in and wiped and set it up as a new phone. I don't think I've done a fresh install since like iOS 4, maybe that cruft contributed to my restore problem.
Unfortunately, doing this appears to wipe out the backup for this device immediately when I logged it in to iCloud. Beware of rely on cloud backups during the betas. (also that once you backup as iOS 9, you can't restore it on 8, but you probably already knew that)