We were on the Fantasy for Christmas in 2012. It was fantastic. The Characters are all dressed up in lovely Holiday attire, like they are dressed for a nice dinner with family. They were all over the ship and there were so many opportunities to have photos with them. The trees all over the ship were absoultely gorgeous. There was Christmas music playing, and I believe Santa Clause was around on Christmas Eve. I can't remember what it was, but Dinner that day was amazing. For some reason< I am thinking it was prime rib. We received a special Christmas poster in our room.
That cruise was (and still is) exceptionally expensive, but I do not regret it for a moment. My kids were 8 & 9 at the time. It was and will probably remain their most memorable Christmas ever.