With iOS 7 now officially out, we had hordes of iPhone users report their experience to PhoneArena through pretty much every possible medium.
Source: http://www.phonearena.com/news/iOS-6-vs-iOS-7-did-performance-drop_id47575
Source: http://www.phonearena.com/news/iOS-6-vs-iOS-7-did-performance-drop_id47575