Was doing some thinking about project Natal, and how it's said to be revolutionary in terms of a gaming experience. While a lot of articles show it promising some cool capabilities, the fact of the matter is, it wont necessarily appeal entirely to hard core gamers. The nintendo Wii for example, has some good motion based controls, and has been great for the casual gamer. Hard core gamers however tend to play for several hours at a time. To be constantly doing interactive motions like that would be impractical for a lot gamers. Let's face it, we're pretty lazy when it comes to gaming. We like the controls to be pretty straight forward and as efficient as possible. The more physical work required from the gamer, the trickier it will be. Something like holding your arms up and aiming for shooting, that's fine for short periods. But imagine having to do that on XBL for your usual call of duty sessions.
I realize that is purely opinion, and maybe a little early to judge it before release. However, it is just my thoughts.