We sailed Dec 17-24 with a full ship of over 3300 passengers and 1300 crew. My son is 11, and my daughter is 16. I wasn't sure whether to do this cruise or go with Disney. But this cruise was a great success, and our kids had a blast!! Even with a full ship the boat rarely seemed too crowded -- except one of the two adult hot tubs was under repair during the cruise. However, there were plenty of times when hot tubs were not crowded. My boy had a great time hanging out on the sports deck playing basketball, volleyball, etc., soaking in the hot tubs, and eating LOTS of food. My daughter is somewhat shy, but she immediately connected with a good group of other teens at the teen lounge called Optix. They had many good activities planned for the teens. One suggestion: this ship is so large get walkie talkies so you can know where your kids are without having to walk everywhere to find them (cell phones aren't an option). They do sell walkie talkies in the ship store too, but we wish we would have brought our own.
All of the families and kids seemed to be very well behaved. We felt very comfortable with our kids hanging out with the others on board, and we are very careful about those things. We saw absolutely no signs of underage drinking, drugs, or other bad behavior. The ship does have good patrols and activities directors to keep mischief at bay.
ONE WARNING: the dollar limit you place on your kid's sea pass card (which acts as a charge card on the ship) does NOT apply to the arcade. I put a $30 limit on my son's card. But this was not explained to us up front, and our boy charged over $100 at the arcade without our knowledge. We complained to guest services and they credited it back to our account, but apparently this is a common problem.
Nice room that comfortably accomodated 2 adults and two older kids. Balcony was nice.