Cool idea!
However, very unsafe to a hamster! 
The movement of walking would be stressful to a hamster, imagine your home being shaken constantly.
Lean forward = game over. The hamster could fall, get stuck, or mess up their entire house.
A minor mishap to humans could be major danger to our pets. Fall down, hamster gets thrown around. Everything would have to be done with a hamster in mind.
Keeping clean. It would be hard to keep everything clean as the cage is exposed to everything.
Sicknesses. This hamster will breath in and be exposed to all types of sick people, including yourself.
Lastly, this cage is tiny! I doubt you could fit a water bottle, wheel, and food! 