very cool - and completely useless as a real gui in my opinion.
I would say it's completely useless as it is right now. But, with some alterations and in combination with the multi-touch screen, it might even improve it's interface.
Notice that in the end, the photographs and web page manipulation is quite impressive, easy, fast and intuitive. On the other hand, on the multi-touch screen video, the while the photographs manipulation is the most interesting part (for me), the photographs are al spread around the screen, with no organization. In that situation, it might be handy to have the pile method.
As for the other features (phisicly realistic colisions, snap to the wall, pile on the air, etc.), i couldn't care less for them