i think nintendo made the right choice. eyetoy proved to me as a gamer that a physical device is needed to get more from gaming. motion sensing tech such as natal or eyetoy is not all so brilliant once the novelty wears off.
Where natal might work extremely well is if they start incorporating this tech with tv's, br players, dvd players, pc's etc.
However, in the fanboy wars, whether Natal is great or not is irrelevant. For MS to succeed, i reckon people will flock to it and carry it whether it does anything for gaming or not.