There's a nice marathon over at gamespot.com that shows all the versions if anyone is on the fence about which to pick r if they want to pick the game up at all
GameSpot Video: Star Wars: The Force Unleashed Gameplay Marathon
Looks like the wii version is pretty much the PSP version. The saber duels do look fun tho on wii so i guess its not all that bad.
Seems like its going to be ok for a star wars game. Certainly not anything groundbreaking, but interesting and entertaining from what they show.
EDIT - HEAVY SPOILER ALERT btw....