We just returned from the Nov. 26 sailing and absolutely enjoyed it. The food was great, ship was very clean, rooms were spacious, and staff was friendly. My husband was not so sure about going on a cruise initially, but he can't wait for the next time we get to go. (That says alot).
My biggest tip is if you dock in Costa Maya. The ship will not tell you anything about Mahahual but I STRONGLY recommend that you go there and skip the port. It's much cheaper, the beach is very nice, drinks are great, food is great, and bartering is easier. Carnival didn't tell anyone about the place, and luckily we did our research. The only ones who seemed to enjoy the port were those who left for the small fishing village of Mahahual.