Finally watched it. Pretty light and fluffy like the other Christmas Specials.
Capaldi was a bit bland in it. I did immediately start scanning all the comic artwork for JB, and was really happy to see the closeups of that Superman comic. I also liked how there were comics from both companies present.
It was also nice that New York was the invasion site for once. Not really much to say about it though. Doesn't seem like something I'd watch again. I thought for sure he was mourning Clara and not River. Bleah.
Watched it. Surprisingly straightforward, no dreams within a dream, or rewriting someone's past, the only nonlinear storytelling bit was a simple flashback.
The "if Superman wore glasses he'd look like Clark Kent" bit probably played on Vaudeville, but I still find it funny.
I also thought he was mourning Clara, but I guess River was the more recent, and at least he's taking the advice of not being alone. Also the "Christmas Tree" he built on the roof was to help fix the time eddies around NYC, so there was a nod to the Ponds, too. I don't want to be watching for Moffat to be saying goodbye to his tics and tropes, but there was a fun capper here:
"That was the Doctor." "Doctor? Doctor who?" "Doctor Mysterio!"
From the point of view of an alien, unfamiliar with comic books and their characters, it "kinda sorta" works..although it emphasizes the 'elderly, absent-minded' side of the Doctor that I haven't really missed.
The pop-culture fanatical Tennant and Smith incarnations would have been geeking out about meeting Stan Lee, not playing 'somebody's grandpa trying to figure out what kids are into these days'.