My paramount complaint with iOS 7 is the overuse of White. There is way too much and even now (after weeks of familiarity) it's a blinding experience to look at the user-interface (UI). It's hard on the eyes, disorienting when trying to discover what elements are clickable, and aesthetically displeasing. I sure hope Apple fixes this or allows users to adopt a black theme when iOS 7 is finally released.
I came across this black themed mockup, man it looks good.
here's link: http://www.flatuitutorials.com/tag/ios-7-flat-ui/
I came across this black themed mockup, man it looks good.

here's link: http://www.flatuitutorials.com/tag/ios-7-flat-ui/