Great game. I have beaten it on multiple occasions. The game is somewhat short, but that can be a good thing too. If every game you ever bought had 200+ hours of gameplay, how would you ever find the time to finish them? I don't mind playing a game that is somewhat short so long as the game play is innovative, fresh, and most of all fun. And I can give you several exaples of games like this right now:
Luigi's Mansion (great game)
Pikmin (awesome game!!!!!!!!!!)
Zack and Wiki (awesome, awesome, awesome game!!!!!!!!!!)
Viewtiful Joe (another awesome gamecube game)
Ikaruga (incredibly short; just five stages, but a great game)
Wii Sports
Also, concerning Luigi's mansion and replay value; I would agree that there is not too much incentive in going back as far as extra content go, but I have found myself playing this game and beating it on different occasions; it is an enjoyable game to play.
Lastly, there are some fun secret ghosts to collect, and I doubt everyone found every cheese mouse and blue ghost the first time through. Also probably most did not get an A+ mansion the first time through either. So there is some replay value there







