Well, I've had a while to use iOS 7. I really like iTunes radio. It seems to learn faster than Pandora, and has a whole lot bigger music library that it plays from.
I do not like the minimalistic wireframe icons and function buttons. They may be real hip and chic (or whatever the cool phrase for being cool is these days), but they are hard to see. A classic case of form over function.
Battery life on my iPad is less running iOS 7. I disable a bunch of stuff the runs in the background (location services, autoupdates, etc.), but the battery life is still shorter than it was running iOS 6.x.
Haven't had a chance to try 7 on my iPhone yet. It is taking a vacation on the mainland. It's visiting relatives at the Apple repair facility in California. I'm limping along on my old iPhone 3G until it returns.