We sailed on Disney Fantasy April 6-13 with three generations of family ranging from ages 4 to 77 (our kids are 4 and 5). This was our first Disney cruise although our family has cruised on other lines.
Generally expectations were met and some surpassed. Disney knows how to make kids happy. Very happy. And keep adults relatively satisfied as well. Service was impeccable. The ship particularly succeeds in its creative details and loads of activities. Complaints are what you would expect of any mass market cruise or amusement park. Yes, there are crowds, the food is average, and there's the near constant upselling. But none of those overly detracted from the experience.
Ship. The Fantasy is a large ship, attractive and well-maintained. The pool deck and buffet (Cabana's) are rather crowded, especially on days at sea. The main pools are small and the area around them tight. Same with the adults pool. There is a good portion of the deck reserved for adults but it's towards the bow and can be quite windy. I especially liked the feel of the Currents bar in the adults area with a nice view of the ship and sea. The Aqua Duck slide is fun but with a 30-45 minute wait a time investment. The atrium and interior areas are highlighted by clever and ever-changing digital art. Other than around meal times most of the ship's interior space is not too crowded. As a runner, I appreciated the .4 mile track on Deck 4, by far the best I've seen on a ship. We particularly liked the bar area in the evenings, especially the Irish pub. Bars are concentrated in a single part of the ship. Again, Disney plays to adults too. As for the ship's size, we definitely noticed it. There's a certain anonymity and impersonality that comes with never seeing the same people twice.