It's a very fun, silly movie. I have a low tolerance for the kind of bathroom jokes that pass for humor in kids' movies (and a lot of adult movies) but I was kept entertained throughout. Sure, it's formulaic, but it's meant to be a parody of all sorts of monster and alien movies, so it's as it should be.
It's loaded with voice talent -- when the opening credits announced that Stephen Colbert plays the President, I laughed just in anticipation of that performance. I was left wondering though, if American viewers of "House" would leave the movie unable to recognize Hugh Laurie using his normal accent.