Went from 8.4.1 on my 5S to 9.0.2 today. Backed up, restored to 9.0.2, activated iMessage and FaceTime, then synced back all my apps. At one point during Sync it stopped for some reason. Restarted the iPhone then syncing continued. No problems. Everything is smooth and fluid. The only annoying thing is that syncing apps back to the phone takes FOREVER. I do not understand. Lightning port is supposed to transfer data at a decent speed, yes? Why does only 64 GB of apps take like six hours to copy? That's only like 2.3 megabits per second of data transfer rate. That's slow EVEN FOR USB 1.0! Come on Apple, you can do better than this!!!