First, I have all 3 so I am pretty much resigned to purchasing all of the peripheral IF it can be shown that they add to the experience.
Natal seems to be to be the weakest as it is not really for gaming. Plus the "tech demo" i.e. scripted video they showed showed only one person being targeted/monitored at any time (racing, pit stop car changing) and did "not" seem like fun. This could mean additional hardware purchase for multiplayer and if it is $200 it would be a hard sell meaning no game support.
Wii Motion Plus attachment is going to be out this year but there is already talk that Wii HD may be around the corner so unless it is going to be forward compatible I do not see a whole lot of games taking advantage of it.
PS3 motion control seems to be somewhere in between wii motion plus and Natal but in my opinion it offers functionality from both types. With the camera even without the use of "Wand" you should be able to mimic stuff from minority report as a new UI.
The use of a wand type controller in games has already been demonstrated via Wii so that can be done as well.
However, IMO the motion control is really not for every genre and seems good for casual gamers (read short gaming sessions) mostly. The genre's I enjoy (RPG) would be too tiring with flailing my arms around for hours unless they do something creative with it. I am not sure how that would pan out.
