Well I'm going to answer that very bluntly and say that yes it was, very good in fact. By far the most Christmassy Christmas Special that Doctor Who has done in a long time and also quite possibly the best one. Now I feel I should get it out of the way and point out that of course I may be slightly biased because of my love of Steven Moffat, but really he's just a talented writer and brought all of his skill to this episode.
'A Christmas Carol' focused upon a very loose retelling of the classic Charles Dickens tale, 'A Christmas Carol'. There are still three ghosts, still a Scrooge like character and of course a poor family whom he must go visit, but this being Doctor Who there must be a twist. For starters, the ghosts were all a product of time travel, with the Doctor literally going into the past to influence events back then or taking someone to the future to show them what they will be like when older. 'A Christmas Carol' is such a Christmas classic, that it's no wonder that this story was chosen as the frame work and with the added benefit of already having time involved, Steven Moffat was able to utilise his patented timey wimey manipulation to genius effect.
This was an episode that heavily relied on guest characters, mostly that of Kazran Sardick (Michael Gambon as the elder version) and Abigail Pettigrew (Katherine Jenkins). Katherine Jenkins didn't have to do much other than sing but Michael Gambon was great as the torn old man who had to suffer through life knowing he could only spend one more day with the person he loved. Amy and Rory* were involved in ancillary plot line about a spaceship they were honeymooning on crashing into a planet, it was the set-up for the main plot of the episode but they spent most of their time in a little exploding room.
The main plot of the episode focused on Kazran Sardick who had control over the planets weather and could quite easily save all 4,003 people on board the ship but because he's a Scrooge he doesn't want, so the Doctor is forced to go back in time to when he was a child and make him a better person as he grows older (yay timey wimey). Of course this inevitably leads to flying sharks and Kazran falling in love with a woman frozen in his fathers dungeon (not as kinky as it sounds). Kazran and Abigail spend every Christmas Eve together for several years, until eventually it is found out that every day she is let out leads her closer to death. So to save his love Kazran vows not to unfreeze her again as she will die.
Now I've skirted around what will probably be the most controversial element of the episode. The fact that fish on this planet fly around in the sky. Steven Moffat gives the Doctor a moment of incredulity to this but then he goes along with it in his normal enthusiastic sense. And really that's all I needed to go along with. It's Doctor Who, anything can happen so I was there from the beginning. Apart from the part when they went on Shark-led sleigh ride, but really that wasn't enough to pull me out. The fish float around in ice crystals in the sky which resonate at the frequency of singing which is why Abigail becomes so important.
Of course by the end of the episode, the ship has been saved and Amy and Rory are fine. But then we also had the show not shying away from the fact that Abigail will indeed die after this last Christmas Day. But she got that last perfect Christmas with the man that she loved which gave everything just the right tone to end the episode on.
This only scraping the surface of why the episode worked, Amy and Rory in those costumes (who knew they were into that?), The Doctor speaking to both the past and present version of Kazran over the video camera and the normal cornucopia of funny lines that Moffat is able to pen ("There isn't any lottery!"). All I can really say about this episode was that it was tremendously fun. It wasn't dark and heavy, it did exactly what it should have done and offered a light and enjoyable Christmas episode. Something feel-good to be enjoyed by the family. It didn't have to resort to childish humour or contrived plot developments, and that's what made it work. Overall an absolutely fantastic Christmas special. Now who can't wait for the main series in March?
*Nice to see Arthur Darvill being bumped up to regular now