I had my first glitch with iOS 7 today. I was watching a YouTube video with a student, then closed the lid to head to my next lesson. When I opened the lid the next time it was right where I left it, but I couldn't get it to rotate to portrait orientation. Tried everything I knew, but nothing worked. All the apps were running just fine and I could switch between them. But it stayed in landscape no matter what. Rebooted to fix it.
A minor glitch, but a glitch nonetheless. Still glad I upgraded. Definitely has some UI improvements.