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.
There is a gym, however, that was quite good (if you overlooked half of the treadmills breaking down after day 3). And I recommend the spin classes. But you need to book on day 1 and there is an additional payment. The deck is not runnable, even though it is sold as a 'running track'. And walking sometimes feels like you are in downtown Tokyo, it is so full.
Choose the right time of year as well. We had huge swells and high winds, resulting in some upper decks being closed. It was so cold the kids didn't use the water slides once. The swells were exciting, but not so the green-gilled children in the dining hall.
Because of the bad weather we spent a lot of time in our cabin. Look at the photo in the brochure and then shrink that considerably. We had a stateroom. I hate to think how parents in a non-stateroom dealt in their little cage. Thank god for the kids' club.
Speaking of the kids' club. They close from 11.45am to 2p.m (right when you need them) and again 4pm to 6pm (right when you need them). But the kids loved it, although for children above 5 (I think) you don't get a pager and they can't check themselves out. So, you either have to check back regularly, or choose to be a masochist and just leave them there with a potential grump (there was one guy whose name I have forgotten who has obviously spent too much time on board because he was a real GRUMP). Mind you, some of the kids were so feral maybe his grumpiness was justified (we witnessed one 10yold push another down a flight of stairs when he didn't get his hat back - and they weren't even brothers exclaimed my kids).
The stop overs where forgettable, the entertainment OK, the entire cruise was too long for us and we spent many hours discussing what type of holiday we should have booked.