Without question. Observing any holiday on a cruise ship is always special and fun. I am sure they will hae Christmas decorations up along with a tree. I am going to be on the Mercury for Thanksgiving and am looking forward to it, as I know the dinner will be simply wonderful.
Are you with child or children? If so, they will be treated to a fantastic event. Not only is the ship "decked to the halls", but even a special visitor arrives! If not, It's always a special time to experience w/ all on board!
Years ago we would go to Vegas a week or so before Christmas because my wife wanted some time to get away from the stress. The place was really decorated up nice. Now the few decorations get lost in all of the other glitter. We asked a bartender friend of ours about the lack of decorations and he said that they don't play it up anymore because a lot of people go to the casinos on Christmas to ease their pain or loneliness during the holidays. We have stopped going around Christmas.
A cruise sounds as a great way to celebrate. As a suggestion you may want to buy and wrap a small gift for some of the crew that will be serving you; eg. room steward, waiter and busperson I am sure that they miss being with their families and would appreciate being remembered on that day. You could also take some wrapping paper and get something on board or in port.
It is my understanding that they will. The cruise originates in San Diego and then cruises the Mexican Riviera for 11 days. We will spend Thanksgiving at sea. I will post a thorough report when I get back.