Sailed out of New Orleans on the Fantasy. Got to the port early and boarded with the first group because we had a boarding upgrade under our chair. Simply listen and follow instructions and it is a piece of cake. The food was great and plentiful. If you set your eating schedule for other than normal times there is very little in the way of a line. There are a lot of activities, just read the Capers. I can not wait to go again and would recommend it to anyone thinking of going. If you are a smoker, you can save enough at the Duty Free on cigs to pay for your cruise(seriously).
There was so much good, but there are a couple of negatives which I will share. On the ship there are ample opportunities to spend money. While in port they will encourage you to do their excursions. While they do guarantee theirs, there are other alternatives that are similiar and a lot cheaper(this was in Progreso).
The other is with the way they charge your credit card. In my case, I had more that ample credit to cover any charges. We were told that the charges would hit our card 3 or 4 days after the cruise. Everytime I use my Sign and Sail they authorized it to my credit card, so when I got off the boat and check the account I had several pending charges. A couple of days later one big charge hit my credit card, with the charges still pending it tied up my available credit. I know it will work itself out but if you were still traveling and depended on that it could be a problem so just be aware.
My best advice is go, enjoy and make friends with an experience cruiser and talk to them about what they have learned.