From the video it appears that the UI lags noticeably behind the user's actual motion. A friend who has demoed Natal mentioned it suffers from a minor lag as w

From the video it appears that the UI lags noticeably behind the user's actual motion. A friend who has demoed Natal mentioned it suffers from a minor lag as well. This strikes me as a major problem when one is expecting the screen view to reflect their current position rather than their future position. For precision tasks it is akin to giving your mouse cursor acceleration and then training yourself to decelerate at the correct thresholds.