During a Branch chat, Daring Fireball's John Gruber has said that iOS 7 is running behind schedule, and that when it is released it'll include a big change to the user interface (UI). He said:
What I've heard: iOS 7 is running behind, and engineers have been pulled from OS X 10.9 to work on it. (Let me know if you've heard this song before.)
Gruber also noted that iOS 7 is set to have a "significant system-wide UI overhaul" and that iOS engineers who are toting the next-gen mobile OS from Apple are required to have a special privacy filter on their devices that reportedly limits viewing angles on their devices. This stops others from getting a look at the new-look iOS.
iOS has needed an UI overhaul for a while now, something I've been itching for since the iPhone 3GS. Android has been making strides in the UI department, something Apple should've been on the ball about. iOS 7 should hopefully be quite striking to both look at, and use.