I think an area where the Wii falls short is, once you get outside of games where the controller is suitable, the 360 kicks the shit out of it. I mention 360 as we have the 360 and Wii and my opinion of Sony is low enough that a Playstation has even less chance than anything EA published making it into this house.
Where Wii is good, it's amazingly good. But outside of titles where that controller shines, I can't see anything it has over it's competitors other than price.... which is a big factor to be sure.