Well, I think it's a good idea, in principle.
However their "prototype" does just look like someone has stuck a bit of metal and black wii nunchucks to the side of a bog standard generic tablet. Should be clip on controllers, and not just look like they were added on as an afterthought.
Also, an i7?? in a Tablet?? It looks to me that the controllers are so far from the main body so that you don't roast your hands. The tablet itself could probably double as a portable hob. Battery life will be terrible. Stick a more efficient processor in, knock £300 off the price and sort out the controllers
After all, people have bought more unwieldy "portable" things, having said that I never did see anyone sat in public with their Sega Game Gear