A Disney Cruise was our happy medium between my wife's sentiment that "Every kids should see Disney" and mine, that "Disney World is the epitome of all that family vacation should NOT be..." This was our second cruise. my wife and I traveled with our kids, ages 10, 8 and 4. From our perspective here are some pros & cons:
+Cleanliness; there's a reason that Disney isn't a part of any stomach flu epidemics. The crew went to extra lengths to keep things clean given recent outbreaks on other cruise lines based out of FL.
+Dolphin & Sea Turtle Adventure in Grand Cayman - our kids may never forget it - pay for the full swim adventure vs the simple encounter - getting towed & pushed by those creatures was amazing.
+Chacchoban Ruins in Costa Maya - added some education to the trip, and were greeted at the final pyramid by some spider monkeys - was also a nice place to get some authentic & cheap souvenirs.
+Cozumel Submarine tour with Atlantis - how many people ever get to go in a sub? & we were lucky enough to see a 4 ft shark , some lionfish and a stingray among many other common fish.
+Cozumel Beach Party at Playa Mia - OK food, great pool for each age of kids, amazing inflatable "obstacle course" out in the ocean, & a staff that held regular games & came around with iguanas & parrots to hold
+Petting, feeding & snorkeling with stingrays at castaway cay
+On Board: Kids area... on "at-sea" days, the boys would've stayed all day
+Food in the nightly restaurants: a lot of people say to pay for the extra meal & go to Palo or Remy - when I can get the kind of quality that the main dining offered & spend the time with my family, I don't see why I'd pay the upcharge
+Shows: 3 were great; 2 were mediocre; One was trumped by the SuperBowl on the jumbo screen on the pool deck
+BYO Alcohol... saved a few dollars with my own rum, & yet still enjoyed the not-too-outrageously priced drinks in the bars & wine at dinner
+Spa & exercise area - can't say enough good about the staff & the equipment - I wish it had 2x the space.
- Pools - if you want a relaxing poolside vacation, go to resort, not a cruise; All the pools are glorified bathtubs.
- Midship in the evening: elevators are a waste of time from 6-9 nightly; If you're not in shape to climb 3-8 flights of stairs several times daily, plan to fight for elevators... I used the stairs to "earn" some extra desserts.
- Buffets at midday: effectively feeding a family of five in Cabanas can wreck your day; go early/late or not at all
- Evening Meal Servers: this is hit or miss... ours missed badly this time - but they were very polite, & once the dining area is 90% empty, keeping your kids under control isn't too important.
- "fireworks at sea" is Way overrated - the pirate night theme is cute for the kids, though
- Aquaduck & Characters lines: lines to remind me about what is wrong with a Disney World vacation... bonus is that you'll happen onto enough slow times in 7 days that you can avoid even these lines
Bottom line: if you go, do it right; Go on Disney, get the room on floor 6 or above (os you can see over the lifeboats), buy what you want, do what you want, go on the excursions you want & forget about prices; you can always make more money... if you try another cruise line & skimp it may be the worst ~$1000 you ever tried to save