We just got off the ship last weekend. For the most part it was a pleasant experience as long as we stayed in the less populated areas. On sea days when everyone was on board the pool areas were jammed. We found the Central Park area very quiet and relaxing and particularly nice during the evening. Giovanni's Table, one of the alternative restaurants, served us one of the best meals we have ever had on any cruise we've taken. Service at the new upscale 150 Central Park was impeccable, although we found the food to be a little less exotic than expected. Even though I don't have much of a sweet tooth, the dessert offering was excellent in this restaurant. Keep in mind that this is a "tasting" menu and the portions are extremely small. This did not present a problem, however, there were some courses that could've benefitted by a little more of a portion to get full flavor the chef was attempting to provide.
Production shows were excellent, but keep in mind that, due to the number of passengers and demand for various venues, EVERYTHING on board should be booked in advance or you may be out of luck. We did book the water show, ice show, and dinner reservations for 150 Central Park through our travel agent prior to embarking. A couple of other decisions were made on the ship and booked through the computer program on the cabin TV. We did this the second day at sea and the choices were already limited to what we could attend. Alternative restaurants are easier to book on formal nights when most people are in the dining rooms.
In short, we would not sail the big ships again. They are just too crowded for our taste. But then, we are seniors who have traveled quite a bit, mostly on the Radiance Class ships, which we much prefer. For families with children and teens, the big ships may be more to your liking due to the many choices of entertainment, etc.