Every single video I've seen of Natal in action doesn't look like it's something that is sustainable. The simple concept of the hardware has far too many glaring flaws for me to believe that it will take off significantly.
1. Many people do not have the space in their living rooms (Much less their bedrooms) to be flailing their bodies and limbs about in the way I've seen demonstrators do on large empty stages.
2. The lack of something to hold or buttons to press will limit the number of games and that speed and accuracy with which games can be played. A controller might be a significant barrier for some people to play games, but it can just as easily be said that the lack of a controller could be just as big a barrier. It's possible that Microsoft could release some kind of controller to work with Natal, but that would completely defy to point of Natal to break the controller barrier and the device could be considered a failure.
3. Almost nothing I've seen beind done with Natal isn't capable of being done with Sony's PlayStation Eye.







