Huge for developers.
Massive for everyone else.
iOS 8 is the biggest iOS release ever — for developers and everyone else. But that wasn’t the goal. We simply set out to create the most natural experience. Each enhancement has a purpose. Every new feature deserves to be a new feature. Each function is more considered, each next step is more efficient. It all adds up to an even better experience — one that is pleasantly surprising at first and becomes utterly indispensable before you know it.
Detail here