We cruised the Conquest on 1/2/05 with an almost 4 year old girl and a 10 year old boy. They loved it, we loved it, the Camp Carnival is great. We were lucky, we took our kids out of school for the cruise, so there weren't many kids on the boat. I have never been on a Disney cruise, but if I'm going to spend that kind of money on Disney, it's going to be at Disney World, which we did a few years ago and had a BLAST!!
I highly recommend the Conquest (out of New Orleans) if you have any specific questions, please let me know.