I think petfrog looks beautiful. I kind of want one.
And yet ... I suspect the whole thing would be crap - usability-wise.
Firstly, I can't find out how big it's meant to be. If it's a handheld, then the Internet Browser example is just bogus. Both the screen and the keyboard are implausibly small. And the "petfrog" logo wastes nearly as much space as either.
I like the fact that the navigation, select and undo buttons are big. But imagine this is something where the screen and keyboard are sensibly big. How big is this navigation window then?
The UI is designed in the same style as the physical unit - the user experience is therefore simple , seamless and most sophisticated for every single application.
Is similarity of "style" really what makes the experience simple, seamless and sophisticated? As far as I can tell, the similarity of style consists of the orange and blue colour schemes, but doesn't stop one bit of the UI being a keyboard, another bit of the UI being a picture of a joystick, and another some amazingly retro virtual reality thang to make finding your MP3s more challenging.
I wonder how they get pseudo-physical feedback on a touch pad? Does it go all bendy due to Piezzo-electric effects or something?