Disney is definitely expensive compared to most of the other brands. We sailed on the Fantasy last fall - their newest ship and, along with the Dream, one of the bigger ones. While all cruise lines have Kids Clubs, Disney's is definitely a step above the rest. It's much bigger, with more activities, character appearances, and planned events. They also have a nursery for babies under 3 years old, which, to my knowledge doesn't exist on any other cruise line. They also offer strollers that you can borrow for your whole cruise at no cost (other than a refundable security deposit).
A lot of people say that the service on Disney is so much better than any other line. I have also sailed on Celebrity, which is somewhat more upscale, and felt that the food and service were better on Celebrity. I have absolutely no complaints at all about Disney's service, but it didn't wow me like Celebrity's. The food on Disney is ok, but not special, in my opinion.
I did think that my room on Disney was nicer than on Celebrity. My favorite feature is the split bathrooms - one with a sink and shower, the other with a sink and toilet. It's SO nice to have them separated. They also offered more closet space and under the bed storage on Disney.
If you get a Deluxe Family Oceanview Stateroom, the porthole on Disney actually has a 5 foot diameter with a built in window seat, so it's pretty big and nice.
The Fantasy had some other fun features - the aquaduck water ride is really fun for kids and adults. They have a detective game that sends you all over the ship looking for clues to solve a mystery, using animated paintings (really LCD screens) to watch the clues.
Disney's private island, Castaway Cay, is also REALLY nice. It's definitely worth a stop!
Anyway, is the price justified? Probably not. But we had a truly amazing vacation last year and planned another one for next summer.