I read Cruise Critic prior to my cruise and - based on the reviews - expected a less than ideal experience. What a bunch of nay-sayers! I found my overall experience to be excellent. The crowds are a given - 4,000+ passengers is a lot no matter how you slice it, and I did find the elevators, buffet, and pool areas crowded (it was especially hard to get a lounge and a spot in one of the hot tubs). However, the staff does an excellent job of minimizing the effects of so many people. Embarkation and disembarkation were seamless, and I rarely had to wait on line for more than a few minutes for anything. The staff were patient and extremely friendly, and the ship was well labeled, which really helped with getting around and making the most of my time.
The food was excellent overall and there were so many choices. There was enough variety at the buffet to keep me satisfied, but I recommend trying the specialty restaurants as well. For an additional charge of $15-$25 per person, you can order as much as you like, and the food and service are well worth it. We especially loved the Japanese (Teppanyaki) and French (Le Bistro) restaurants - delicious and very elegant! Make sure to try O-Sheehans, too, which does not require an extra fee (great fish & chips and ice cream sundaes!) One tip if you eat at the buffet. Finding seating can be a challenge at peak times, but there is additional seating in La Cucina restaurant, one floor below the buffet. Most people didn't seem to know about it, and it was a much quieter and more relaxing place to sit and eat.
The entertainment on board was excellent as well. My favorite was Cirque Dreams. If you like Cirque du Soleil type shows, you won't be disappointed. Blue Man group was just okay for me, but the kids in our group LOVED it. Legends was fun - Steven Tyler stole the show and the others were good, but not exceptional. The on-board activities were plentiful and the cruise director and his staff did a great job of making everything fun and lively. I enjoyed bingo, Deal or No Deal, and Dancing with the Stars as well as the themed music parties on deck and at Bliss lounge.
Regarding excursions, we had a positive experience overall and found them a good way to spend our time at ports of call since there's just not enough time to really explore the islands on your own. The snorkeling experience in St. Thomas was a bast and the dolphin swim in Nassau was amazing (surpassed my expectations). In St. Maarten we did the beach bash, which wasn't really worth it. It was really just transportation to the beach and a lounge chair. You can probably take a taxi on your own more inexpensively if you just want a day at the beach.
We took this cruise with a large family group and it was ideal for this type of travel - lots of things for people of all ages to do and great balance of together and personal time. I can't say enough good things about the experience.