Motions controls work for little things. For example, I wouldn't play a Wii game with the motion sensor, I'd only play a Wii game I could use the Gamecube controller on. It's a gimmick and doesn't work for playing games properly, it's supposed to let people around you get a laugh and for you find trying twice as hard to play half as well fun, somehow.
The PS3 motion sensing works. Like, shaking off the octocamo in MGS4 by rattling the controller, that's practical, or tipping the controller backwards in GTA IV to reload a gun, that's practical. Flying a helicopter in GTA IV with it is NOT practical, it's twice as hard, and not fun.
I think what I'm saying is, you should make a game WITHOUT the motion controls, and then add EXTRA stuff that uses them. Little things, like the reloading in GTA IV, or the balancing on logs in Uncharted. You shouldn't build games around them.