WWDC 2013: iOS7 is "the biggest change since the iPhone’’.

The lyrics are from Apple's CEO Tim Cook on stage at WWDC, when announcing the next major version of the operating system
that powers the iPhone, iPad and iPod Touch.

Pending its release, we can note that, the design is the biggest change. Henceforth a translucent look can be seen everywhere from the lockscreen, to the keyboard.

In addition iOS 7 brings lots of color and animations to improve the experience.