Great cruise with a great crew. Everyone was always smiling, the crew was attentive, and the experience was just wonderful overall.
I cruised solo, but always found something to do on-board and spent the time either reading or on a shore excursion. The ship made port in typical tourist destinations, but being a scuba diver, it didn't matter; the excursions were great once you got under the water. On-board, the dining was good, but the REAL highlight was the Chef's Table with Chef Fabian - undoubtedly the best dinner I've ever had in my life. It started with a walk through the galley with complimentary champagne, an explanation of how everything was coordinated, the costs and personnel involved, and a small appetizer and a demonstration of how to make an most delicious chocolate cake while we were still in the galley. After that, we were taken to a private dining table in a room and served 7 of the most delicious courses (with our choice of red or white wine) I've ever had the pleasure of eating. After we were served, everyone paused as Chef Fabian explained how the dish was made, why the ingredients were chosen, why the sauces were chosen, and the techniques involved in crafting it. Many of the dishes we were served were made using cutting edge techniques that had only been discovered in the past few years. It was truly a night to remember; the $75 price tag is an amazing price for such a gourmet dinner and experience. If you're a foodie, or just someone who likes to tinker in the kitchen on a lazy Saturday night, you owe it to yourself to try this experience.
That said, the rest of the cruise, there were a lot of young families and senior citizens and most of the activities seemed geared towards them. From the kids clubs to the bingo and the lido deck activities, Carnival knows where their bread and butter resides. Aside from the after dinner shows and late-night comedians (both of which were very enjoyable), there wasn't much in the way of interesting activities for those in their 20's and 30's without kids; the shore excursions were the best the ship had to offer most of the time, and by the end of the 7 day cruise, I felt like I had experienced everything the ship had to offer and had no regrets about debarking.
Talk about a tourist trap; the shop keeps were money-grubbing and aggressive. Every time you tried to leave, they'd start making offers, taking 10, 20, 30% off on an item you were only casually looking at, saying anything to stop you. Often times if you're in the mood to haggle, you can cut the price of anything they offer in half, whether it's a $10 trinket or a $1,000 chess set, everything is COMPLETELY overpriced, and you're expected to haggle.
Even after haggling over something you really want, threatening to walk away, actually walking away then being offered a better deal, etc - I still came away from the port feeling like I had been ripped off on everything except the tequila (where the prices are set, non-negotiable, and in line with the cruise ship and every other duty-free port).
Unless you're planning to do some diving, sightseeing, or buy some tequila, then Cozumel, and most of Mexico, really don't have anything to offer.