Think of this game as Spongio Party...
The game is pretty entertaining overall. You play through several series of mini games that range from totally easy, to totally inane, to pretty fun. The game has a good learning curve to it, it starts off easier and moves into the better games by the end. Throughout the game it keeps track of these points that allow your character to get the starring villain role in the movie being made (hence the title).
We skipped through the story cut scenes, but I can still give you the jist of it: Mermaid Man and Barnacle Boy have to do some stuff, and save some stuff from the villain (who you star as). Yeah, something like that, I dunno. We had kinda lost interest, honestly. The ending is pretty cool, actually. It plays out for a LONG time (probably around 30 minutes) so it's quite rewarding to make it through everything. As you play you'll unlock artwork and statues of things from the show, which is a nice touch, but not terribly interesting.
Sound and controls are pretty tight, all things considering. Voice work all seems to come directly from the actors and controls are varied between games, yet simple enough to be easily accessible. It's a fun experience that a kid of any age could enjoy (I myself am in my 20's).
Bottom line: While it is a game geared towards kids, it's still enjoyable to an extent, even for an adult. The game wears out pretty quickly though (maybe 3 hours or so) so don't expect an epic gaming experience...but who was expecting that from this game to begin with? If you like Mario Party games it's a no brainer that you'd like this.