Well, I finally broke down and went to see it. I was hesitant after reading all the pans here. Egad! It was a great movie! You can't compare it to the "original" any more than you can compare "Scrooge" to the eternal Dickens classic. It has a life of its own. Jim Carrey was amazing. How he can deliver so many feelings and emotions behind 10 pounds of latex is fantastic. Some of his scenes (obviously impromptu) were so funny I nearly wet myself. The sets were great and not nearly as over-blown as I had expected. As for the "prequel" portion, well, it was only so-so. The best part of the whole show is when they sing the "Ah hoo torres" song at the end which has ALWAYS been my most favorite Christmas song ever.
I recommend the movie highly to kids and adults. As for the negative comments on imdb.com I gotta say..."get over it, ya big bunch of grinches!!!!!"