I have updated my iPhone to iOS 7 and I'm still getting used to it.  For example, it took me 2 days to figure out how to close apps that were running in the background (by the way, once in an app, just press the home button twice and all running apps will appear.  Then just swipe each one upward to close them).

If you're wondering why Apple decided this new system was the way to go, here is there official video.