My main concern is that Nintendo needs to convince us that this betters gaming, and that this is the future of gaming, and not just the ultimate gimmick. They still haven't even made the case that the DS is "better". It's just different. Often times annoying.
The idea of swinging a sword sounds cool, but weren't we fine pressing a button? It was fast and simple. Doesn't sword swinging, even if it's just a nudge of the wrist, exert more energy than necessary to accomplish that act, especially since it's so highly repetitive? I really don't think I want to wiggle my hand through a whole game of Zelda, while hanging onto some completely separate control stick accessory with my other hand...
I PRAY that Nintendo has thought this through, VERY deeply, and that their video examples are strictly theoretical. I HOPE they don't force new control movements just because they're possible. They may think they're immersing us, but if people have to stop playing Zelda after 15 minutes to give their hands a break, that would be a serious problem.
And these are just natural concerns to have at this point, IMO.