The vita sensor doesn't seem to serve any real purpose. It's supposed to check your hartrate during a game to check exitement(for example scary parts), but doesn't the game already have to be scary to get your heartrate up in te first place? It doesn't make sence, so then al is left is another fitness gimmick.
To be real honest here Wii has been a great succes for Nintendo, but they better come up with something better otherwise they will fail next gen. Because by next gen everyone will have capable motion controls, and with lost 3rd party support Nintendo might be in trouble(they will probably have to lower the price of the Wii already after Natal and Arc release).