It's amazing but I personally never saw it fore real! Can we imagine Michelangelo doing it 500 years ago? And it's still there! This is the time where things comes and go, but some things are out of time! Maybe the hand was the last thing he did, and he was pretty bored to beat that hard rock :D!
Btw I think it's stunning mostly because of the age it represents, it's a symbol of an era where art exploded in quality and realism.