We were on Horizon for Christmas prior to the pandemic, and I hate to be negative but we will not do it again. Of course it is different for each family (ages of the kids, etc) but our kids (who were roughly 13 and 21 at the time) both said they'd rather be home for Christmas.
We found that the cruise industry is very cyclical, and (at least for us) we did not find they did a lot of things special for Christmas (it was kind of like any other cruise). Granted there were very nice Christmas decorations, formal night/dinner was Christmas dinner, etc.
We did take our own little "pop up" type Christmas tree for the cabin and a few small gifts for the kids (but we had to fly across the country so space was limited). But that brings me to our next "never again" ... we will never fly across the county at Christmas time again. Extremely expensive airfare, crazy busy airports, overbooked airlines, weather issues, etc. Everywhere you go, everything you do (before/during/after the cruise) will be absolutely packed. Hotels are very expensive, very booked up.
But I will admit, Christmas on a ship is way less work for Mom. 😄
Having said all that, I would love to go in early December when all the decorations are up, etc. but before the holiday crowds set in.