(WARNING: story and plot twists discussed in explicit detail, so--watch the episode first!)
And finally after ten years of Whovian Christmas Specials (the only thing I actually look forward to when the season rolls by) the Big Man himself shows up. And when he makes his entrance (I mean a proper entrance, unlike the earlier rooftop scene where he attempted to remain incognito) it has to be in style. An explosion takes out a wall; tangerines roll (like bowled grenades?) across the floor; Slinkies march forth, followed by regiments of toy robots. The Big Man himself strides in in the guise of Nick Frost wearing a luxurious white beard and red suit, levels at the camera (at us in effect) his most 'I'm not taking any crap from you' Robert Baratheon glare and growls: "what seems to be the problem?"
It's Last Christmas, the latest holiday special (a tradition since the series' regeneration), and first to feature the Twelfth Doctor, played by Peter Capaldi. It's scary ("I want you to picture it this way: somebody has put a straw right through your skull and is drinking you"), funny ("All I could see was his nose, with all the little hairs coming out of it. Have you seen those? It's like he's got insects trapped up there, all trying to escape with their wee, wiggly legs") and not a little sad ("Do you know why people get together at Christmas? Because every time they do, it might be the last time"). It's also present showrunner Steven Moffat's fifth attempt, and perhaps now more than ever he's got the mixture (scary, funny, and sad) just right.
We get Santa on a reindeer rearing on its hind legs, nose flaring like a landing strip beacon; we get monsters with hideously sticky mouths that slowly open and reveal--most horrific of all--human mouths (the monsters perch on peoples' faces); we get Danny and Clara enjoying Christmas Day (or do they?); we get a girl walking past deadly telepathic aliens, trying to lull them by singing and dancing to the tune of Slade's hokey "Merry X-mas Everybody" (So here it is Merry Christmas, everybody's having fun; look to the future now, it's only just begun). Half the suspense comes from the fact that the girl's eyes are closed, her dancing so energetic she's liable to kick one of the creatures awake before she's past.
I love the time Danny (Samuel Anderson) and Clara (Jenna Coleman) manage to spend together after what happened in the last episode; as Danny puts it the moment is a gift, one Clara should treasure before putting aside (Danny being the Danny she remembers, he's self-sacrificingly noble). I love the Doctor's spiky relationship with Santa ("Why don't you just go and, and make a naughty list?" "I have, mate, and you're on it!") and how they're grudgingly forced to work together, two myths come to sudden life and sharing space in a screen much too small to properly accommodate their outsized egos (couldn't Frost's Santa come back once in a while--guest-star in another Christmas Special? Please?).
Viewers have noted how the episode borrows from certain films--Alien comes to mind (the facehuggers anyone?), the resemblance noted upon then summarily and hilariously dismissed ("There's a horror movie called Alien? That's really offensive. No wonder everyone keeps invading you!"); I'd go further and say while the big-screen creature messes with one's gut (think digger wasps), the small-screen version messes with one's mind, which I find more unsettling despite the PG rating. Inception is another movie (dream within a dream within a), though I'm entirely comfortable saying Moffat's take is an improvement (for one the episode hews closer to dream logic than plot logic, unlike Nolan's singularly unimaginative picture; for another Moffat's dialogue sparkles where Nolan's chugs like a cargo diesel).
Finally I love how Moffat keeps digging away at the meaning of terms, unearthing more and more significance behind material previously thought to be mined out--case in point being the episode's title. "Last Christmas" at first blush refers to the possibility that if the aliens succeed then goodbye humanity--a last Christmas, literally. It could mean second chances, that we may be grown up but for old times' sake (and the plot's success) we need to believe in Christmas one more time. It could also--and most poignantly--mean what Danny says: that every Christmas could be our last, and we should treat each one (and each other) as if it was.
The episode equates Santa with The Doctor, or the two at least regard each other as near-equals; the show also posts a clever reply to the question of Santa's existence: of course he's a dream, but insofar as dreams have the power to harm as well as inspire, he's a necessary dream. Same with The Doctor; about as real (maybe less), as loved (maybe more), and a requirement for the health of our sanity.
And yes there is a hint or suggestion--fist-sized, of a rough citrus shade--that perhaps by episode's end we haven't awakened from the dream, that we need to continue believing in The Doctor (even as a mere imaginary construct developed for our entertainment) no matter what, because the alternative is well nigh unbearable.