This is why you have a back up, if you do not like it, you go back to your back and up voila! just as you had it before. There is no gun to your head to use the new OS (unless you bought a new phone).
The bugs I have encounter with OS X updates have been very very minor since the very beginning. The worst usually involves printers. If you really do not like iOS 7, then an iPhone is obviously not the phone for you. You can still use iOS 6, but eventually it will be outdated and apps will require iOS 7 to run. At that point it is time to move to Android, Windows or whatever else is out there. If it does not work for you, then get what does.