Allen Pikes post get's it mostly right, but I think the 'Copy This, Assholes' is a bit off the mark. iOS7 is just Apple consistently doing what it's done for the past decade or so - steadily pushing the state of the art:

Even with tuned native software, the iPhone 4′s A4 chip can’t handle the most interesting aspects of iOS 7. The 3D, the blur, the compositing – all of them are disabled or degraded on the A4. iOS 7 is designed and developed for the A5, and will truly shine on the A7.

The original iPhone and iOS pushed the state of the art of 2007. After many iterations of hardware improvements, iOS is again able to push the envelope. This shouldn't be a surprise, but to many, it kind of is. And I think that's because not many corporations are able to envision the future and have the infrastructure and culture in place to relentlessly execute that vision the way Apple does.

It's not something we're used to seeing so consistently from a multi-billion-dollar corporation, and I think it's brilliant.