I got the Wii version of the game. I think it's a nice companion piece to the 360/PS3 version. The co-op is fun and the controls, while they do take awhile to get down are decent. I honestly think RedFly's version is in some ways funnier, due to thier take on certain events (i.e. When he's supposedly ‘pinned down’ on the stairs by StayPuft's little mini minions) and the animation is a little better.
That said, the Wii version is VERY easy. Played on the hardest difficulty will give you a little bit of a challenge, but not compared to the other version. Also, the AI is, at times, questionable. There have been many times where I'm fighting ghosts and my teammates will just stand there and watch. Also, ghosts will occasionally just float around as you blast and eventually trap them.
Still, the versions are different enough that I don't feel bad about either purchase, and I can definately forsee times where I'll want to play one or the other.
Bonus round: The art on the Wii disk is the first fully colored label I've seen on one. Instead of that one/two toned and transparent job they usually do, so a kudos for that choice too.