Don't touch iOS 9.0.2!
I tried iOS 9.0.2 on my iPhone 5s and iPad 4th gen. and ran into various problems.
My iPhone lost my music playlists all of a sudden, froze sporadically and seemed to drain the battery.
My iPad was no longer able to unlock and use my SIM card. Whenever the correct PIN was entered it ended within a deadlock. Incorrect PIN entries where noticed, though.
=> I downgraded to 9.0.1 and recommended to wait for a proper 9.x release from Apple.