We went back in 2013, my boys were 18, 13 & 11. My younger two had a blast, couldn't get them out of the kids club. My oldest kinda felt a little lost. Too old for the kids clubs, not old enough to drink in the other clubs, and didn't know anyone. We all enjoyed Castaway Cay, 2 of the kids did the parasailing, the middle one rented a bike instead. I enjoyed the adults only pool and we all had fun on the Aquacoaster.
If we ever go again, I don't think it will be a Disney cruise. They would rather go on a ship with more adult things to do. Although we do have a little one now so maybe I'll go again but not sure if her uncles would go.
I will say it's very pricey but it was a fun trip. We added a 4 day/3 night cruise at the end of a parks trip. At the time, all the boys decided they liked the cruise more than the parks.