Let me start by saying the kids loved it. Let me continue by issuing a word of warning - just because your kids love it doesn't mean you will.
If you do not like crowds, queues, kitsch, or corny entertainment, and you do not drink copious amounts of alcohol, then this is not the holiday for you. We went out of school holidays but the boat was full of people and there were lots of kids. This wasn't so much of an issues as long as you don't mind waiting in long queues for breakfast with people you would be convinced have not eaten for a month (judging by the size of their plates), but you know that can't possible be so (judging by the size of their bodies).
The food itself was good, but there was so little else to do on the boat that didn't require additional charge, that eating itself became the entertainment and there were times we groaned when 12 o'clock and 6 o'clock came around.