When I first watched this demo it felt like a novelty, but the more I thought about it the more potential I saw to organize content in a more dynamic and flexible way.

What I like most about this interface is that it is not trying to teach us a new method of interaction. Instead it is trying to replicate something we are already familiar with. The idea of using metaphors we already understand is a staple of interface design and is what makes things like tabs, desktops and folders so successful.