My view is that Natal is more different from the Eye than some would have you believe, and less different than others would have you believe.
There seems little doubt Natal has some useful extra abilities, although until the Wand launches and we see it's full feature set it's hard to compare them fully as some features supported by Natal seem intended to be supported by an Eye/Wand combination on the PS3.
Personally, I'm very interested in Natal but not for games - I'm actually much more interested in it as a general interface for your PC vs actually playing games with it.
Try to be reasonable... its easier than you think...