As it has always been, it's the small things that make the Disney difference. The Fantasy is an incredibly beautiful ship, where Disney touches abound. They didn't cheap out on anything on the Fantasy. The food, service, shows kids' clubs and staterooms were all top-notch.
The Fantasy's biggest strength in my opinion is ambiance. From over-the-top bathrooms featuring mosaics of bullfighters and flamenco dancers to the custom carpets and artwork featured around the ship, the Fantasy is unparalleled if you like details. We were particularly impressed with the theming at Cabanas, the lido deck buffet. It features a full-wall Finding Nemo mosaic that is truly beautiful.
Also strong (as expected) is the service. These cast members are trained impeccably. I can't think of a single encounter I had that wasn't exemplary.
We loved the food. Once again, I found myself impressed with Cabanas. I've never been overly fond of buffets, but this one was really good, especially at lunch. The main dining room food was also excellent, but the gem here again is the service. On DCL, you switch dining rooms each night, but your waiter follows you.
I have two very minor complaints. First, none of our party (9 people total) enjoyed the lounge singers. I thought Disney could have done better here...in fact a few were downright bad.
Second, I wasn't overly impressed with the port adventures. I'm not saying they were terrible (at all), but for the cost, I thought they could have been better. Our ports were Grand Cayman, Costa Maya, Cozumel and Castaway Cay.