iOS 7 changes the backgrounding model, which has been a giant point of contention since the app store was introduced, and also has a brand new facelift. It was also one of the main differentiators aside from data sharing between apps between iOS and android. It is not a trivial update technologically or a small update from a marketing and direction standpoint.

It is also the first major OS update under Ive and Cook's direction.

The phones are a minor update, as to be expected like every S release.