Of course I was one of the people who voted Fantastic. Its nice for the family to gather around and watch SpongeBob, but its even better when there's a Christmas special for it to get in the holiday spirit. As for Santa Clause, my theory is that he first discovered that sea creatures were beginning to celebrate Christmas, so he packed extra presents and took his sleigh to the ocean to see all the bottled letters. The problem was since it was first time, he had trouble figuring out how to get underwater, but he finally did in the afternoon of Christmas, by either using magic or an invisible air bubble was surrounding his whole sleigh and reindeer. Once he got there he noticed Squidward gave all the presents to the Bikini Bottomites, so someone already did his job for him. So he used his magic again and poofed him a letter saying he's been a very good boy this year for doing good deeds like that. So that's it then!
In total whatever the correct theory is, it was one fantastic Christmas special, and was made out perfectly with that holiday/spiritual essence of Christmas (and magic! ) (Just like I think the same thing was for D & J...)