i have the same issue, when i tried to choose another background it took a long time to come up with the preview. also i noticed that when i try to unlock the device and write down my PIN it takes time and its lagging
so we went from iOS 4 to 5 to 6 and now 7 and still the same thing that bug me exist. NOTIFICATIONS During CALLS
is it just me or its solved but i didn't hear about it.
Finally it started to show on the iTunes for my iPhone and for my iPad it's preparing the update.
congratulations for those who got it and enjoying it already. can't wait to get it on my devices