How do you KNOW? YOU DON'T. Nintendo isn't stupid. They have lots of people and lots of time to work with this thing. If it feels uncomfortable, I THINK SOMEONE WILL NOTICE. The japanese, IIRC, have hands like everyone else. I don't think they're unable to tell when something doesn't feel right.
GAHD. Some of you people are just being ridiculously superficial and overly-pessimistic. I can totally understand being unsure about this, but we still don't even know that much about the controller. I'm not saying that it can't possibly fail, JUST WAIT UNTIL YOU'VE TRIED IT.