Haha! That's a pretty cool little contraption!
I do have a couple of concerns... I'd worry about it hitting my heels while I walk and secondly, I'd hate to fall and be impaled! But I can see how it might be very useful for someone who cannot carry a pack.
I saw a man walking with something like this only bigger and it was loaded down with things. He didn't look very happy. I always wondered what happened when he was going downhill. Seems like it would gain speed and run right over him.