Looks like a definite upgrade, however I still question how many games this is actually going to be used in. Both Nintendo and Sega have a long history of trying to make add-ons that never caught on in the market place.
For instance it took me watching this 4 minute video plus quite a bit of Wii use to fully understand how exactly this product improves Wii gameplay, I can see this hitting the market and the average causal gamer wondering why they're selling an add-on that does exactly what the Wii mote already does.