Aesthetically I don't see much to fault except the game center icon not being very flat.
The real question isn't the veneer though, it's how it actually works. Everything has to feel smooth and logical and intuitive in actual use. Windows Metro looks great and new versions of Android look nice as well, the issue is the subtle little tweaks and refinements in the UI. Things like the right menu opening when expected.
If Apple has nailed those details, the sky really might be the limit for them.
The real question isn't the veneer though, it's how it actually works. Everything has to feel smooth and logical and intuitive in actual use. Windows Metro looks great and new versions of Android look nice as well, the issue is the subtle little tweaks and refinements in the UI. Things like the right menu opening when expected.
If Apple has nailed those details, the sky really might be the limit for them.