I picked this game up today at Meijer* (I was very surprised to see it out...) and have been able to put some time into it. I Must say, this is a very fun game. The gameplay is very similar to the N64 version, with the major difference being the amount of fun minigames. I especially like the "Fight Mecha-Bowser!" game. In short, go buy this. NOW.
*Meijer is having a buy-1-get-1-half-off sale today on all games, but today only. I also picked up the new Kirby for the GBA for $15ish, a very good deal indeed.