IGN Wii has a preview up for the upcoming Wii version of the game.  IGN says the game employs a ‘sandbox’ style of gameplay similar to Grand Theft Auto.  They also go on to compliment the game’s use of the Wiimote/nunchuk:

The Wii-specific controls for the game seem remarkably well put together. Once Harry’s wand is drawn, the Wiimote can be used to directly control the spells you cast. Everything is handled through accelerometers; there is no pointing in the game whatsoever. Any of the game’s spells can be cast quickly and easily, merely by a flick of the wrist. Thrust the Wiimote forward, and Harry will propel an object away from himself. Motion upward with both the Wiimote and nunchuk, and Harry will cause an object to levitate in the air.

Harry Potter sounds like it could be a good game, but I’ll hold out on this one probably.  Fans of the series may want to check the preview out here.