Well the public beta started earlier than I'd heard but I must say I'm bloody impressed.
And I say that as the former owner of an iPhone 4, and a DesireHD.
Really impressive development (I say as an architect), and I must admit I'm a fanboy of the MetroUI team.
Either way, add your experiences, or your opinions (based on other reviews/videos) just make sure its obvious we know if you've got it on a device in your hand, or are erm, based on 3rd party info.