Carnival decorates the ship with Christmas wreaths and trees. They even have a menorah for Hannukkah. Christmas music plays throughout the voyage and there is a special Christmas show on the first night. All in all it is pretty festive!
Thanks so much for your reply. This will be our 5th cruise (just returned off the Valor 3 weeks ago), and thought we would try the Christmas cruise. We are taking our 23 and 25 year old kids, their spouses and kids with us so we want to make it memorable for them all.