TheNextWeb: Google Finds Its Design Voice On iOS:

The string of well designed, if not exactly perfect, app updates continued. In no particular order, YouTube, Chrome, Google Search, YouTube Capture and of course, Google Maps all displayed a much surer design hand on Apple’s platform. They obeyed the right conventions for things like the back button and the bottom-oriented navigation bar, but they maintained a sense of what Google has been about from the beginning.

Because Apple established strong human interface guidelines*, Google knows where to break them to make apps that feel both at home on iOS and ‘Google-y’. Once you know the guidelines, you can break them.

When you have no design guidelines you have no foil act against. This is why it’s taken Android’s UI design so long to evolve. While far from perfect, Apple App Store Rules and Human Interface Guidelines have made developers a ton of money and created thousands of well-designed mobile applications. Android can be as open as the ocean but restrictions can be a good thing too.

*Notice how Apple refers to them as guidelines, not rules. You get in trouble for breaking rules, whereas guidelines are just, guidelines.

And seriously, if you haven’t read through the HIG yet, do it. You’ll see there’s a method to Apple’s madness. It’s not all bevels and drop shadows.