SPOILERS BEHIND THE CUTS
Amy and Rory, enjoying a part of their honeymoon in the honeymoon suite of a luxury cruise starship, wind up in a bit of a pickle when their ship is caught in a rather nasty storm that prevents them from landing safely. The storm also prevents The Doctor from using the TARDIS to save them and the other people on-board the ship. And the rich, miserly Mr. Kazran Sardick - whose father built the device that controls the skies and the only living man able to control the device that might stop the storm - won't do it. Even at the beset of The Doctor, The President and the 4,000+ people on-board the ship begging for their lives, he sees no reason to have to lift a finger to help others even when it won't cost him a thing.
Faced with a man who has no sense of pity or The Christmas Spirit, The Doctor has no choice but to break the laws of time in order to go back and give him some, playing the Ghosts of Christmas Past, Present and Future in order to save his companions and the soul of a man most consider beyond all hope.
THE GOOD PARTS
* Steven Moffat's script is a delight. "Christmas Carol" episodes of sit-coms and dramas tend to be the most bland, predictable form of Christmas special there is. And yet, despite the unoriginal title and the fact that we know damn well just what the story we're viewing is (i.e. a rehash of one of the most famous works of English literature in the 19th century), there is just enough original material - including a romantic subplot - to make you forget that you've already read much of this story before.
* Michael Gambon is a most effective Scrooge and his turn here as the elder/Present Day Kazran Sardick will stun those who are only familiar with Gambon's portrayal of Albus Dumbledore in all the Harry Potter films since Prisoner of Azkaban. He perfectly captures the evil of The Scrooge character - one who commits evil not through malice, but through indifference. He doesn't wish to cause others pain - he just doesn't care to prevent suffering.
* Matt Smith really comes into his own playing The Doctor in this episode. Freed from his companions for the better part of the episode, we get an analysis of The Eleventh Doctor's character and how he views people that was somewhat lacking in many of the Series 5 episodes which centered more upon Amy Pond.
* Amy and Rory spending the entire episode in their policewoman/centurion costumes. Why? No explanation is given other than "they were in the honeymoon suite" and no further explanation should be needed, unless you are as pure as the driven snow. Suffice it to say, I'm sure some fan-fiction has already been written.
* The shark. Just... everything with The shark.
* Great music, particularly from a special guest performer who made her acting debut in this episode. Again, I can't say anything until you've seen it.
* Rory is still delighting me as a character, though he doesn't get much to do this time around. Marriage does not seem to have mellowed him and while he and The Doctor do still have the understanding that they developed at the end of Season 5, Rory is still very snarky about his wife's devotion to The Doctor seeming to be greater than her devotion to him and is quick to point out The Doctor's many mistakes.
* The biggest problem with this episode only becomes apparent after one is finished watching it. Because it is only then that one realizes just how many of the Rules of Time The Doctor violated throughout the course of this episode.
1. Crossing his own timeline, which is supposed to be impossible.
2. Risking a paradox by allowing two versions of the same person from different points in time to meet, which - the Series One episode Father's Day told us - is a VERY BAD THING that weakens the time stream to the point of breaking and causes paradox-eating monsters to show up and "fix" the damage.
3. Changing the course of one prominent life that has already been set by history, which Waters of Mars made clear was an INCREDIBLY AWFULLY BAD THING to do. Even with good intentions.
* There's also the problem of the teenage Kazran Sardick suddenly deciding not to tell The Doctor about what the numbers on the cryogenic freezer mean or about the illness that the love of his life has. Given everything he's seen The Doctor do in his apparent travels on the TARDIS, you'd think the first thing he'd ask would be if The Doctor might save Abigail. I know we need to set up the tragic romance for the final act... but still... you think he'd ask.
* For that matter, why doesn't Abigail think to ask The Doctor herself? She asks him, upon meeting him, if he is one of her doctors and the subject of why she'd ask that question is never raised.
* For that matter, one has to wonder why The Doctor doesn't put two and two together regarding Abigail's illness and the timer on her cryo unit. Granting that Smith's Doctor is a bit oblivious and that he is under quite a bit of pressure at the moment (in theory anyway - more on this in a bit) throughout the episode, you'd think he'd figure something was up.
* There's also very little sense of urgency regarding Amy and Rory's predicament during some parts of the Episode. Of course with the TARDIS, time is on The Doctor's side but it is easy to forget about them when The Doctor takes a goodly amount of time to take Abigail and Kazran joyriding about the Universe.
* The complication in the third act that The Doctor has changed Kazran so much that the electronic device controlling the clouds that responds to his brainwave patterns no longer recognizes him doesn't make any sense given that the machine should have adjusted along with Kazran's memories as time went by.
* Finally, on a personal note... The Eleventh Doctor has got to be the only person in the universe who would view marriage to Marilyn Monroe as an annoyance.
The Final Verdict: Overall, a most excellent episode. There's quite a few plot holes that you could drive a space whale through and the Laws of Time which has governed the show for so long are violated to rather muted effect. Still, the guest performances are engaging and Matt Smith himself shines in what has to be his single best performance as The Doctor thus far in his career.