That had a lot to like. I don't think it was particulalry good as a Christmas special (which probably needed a bit more going on. This felt quite cheap in places with its small cast, minimal location work and main featured set being the largely made from stock 60's Tardis), but if it had gone out at the end of season 10 as that sort of subverting expectations contemplative finale US shows sometimes do (Buffy season 4 or the final Babylon 5) it would mostly be quite watchable.
Bradley and Capaldi had great chemistry, Gatiss could do that sort of role in his sleep and was very entertaining (though not really personally bothered about it retconning a previous name for his Great Grandad from the books so I'll be sticking to the intent. Making it a great uncle veers it into Spaceballs "Your cousin's uncle's room-mate territory) and the idea there wasn't really a threat was a nice twist. Though yeah, it was basically a benign version of Missy's plot in Death in Heaven. But then the poor Moff run out of new ideas about two years ago anyway.
Also, whilst I think revisiting a 51 year old story was insane (opening with a "709 episodes ago" caption of 4:3 black and white feels like it should have been off-putting to casuals), the recreations of the Tenth Planet we did see were stunning. Just a shame most of that was cut out after they'd gone to the effort! I've a feeling the recap was originally going to be all refilmed before they hit on the morph idea as a way of including Bill.
And Whitaker was fine in her brief scene, though I was mainly glad it was too the point after the lengthy goodbye from 12, I still remember being worn out by Matt Smith going on and on after Tennant's goodbye tour had passed the natural end point of the episode.
The regeneration itself though felt a bit rubbish, too close to End of Time without being as impressive. I think the final speech itself was also hurt by Murray Gold sounding like he was just slapping stock music over the top of it that never seems to quite relate to what's on screen.
But the big thing for me, and probably disproportionately I must admit, was the First Doctor as a sexist. Which was just not very true to his original character. Across three years and a 100 odd episodes you can find biggoted stuff representing the time, but it's very much the in the minority for an irascible but likeable character who could be patronising to the young and perhaps humans generally. Hell, there's probably more racism from the character (though still not a lot) and the episode didn't dare touch that (well, apart from the comment about the French. That's the First Doctor who ****ing loved the French and was excited both times he went there), as if sexism is just funnier.
Now I've had it argued to me that the recreated First Doctor was just being used here to channel and discuss 1960's attitudes. And as an idea I'd not have a problem with that, indeed it'd probably be more Christmas than anything else in the episode. How many people watching were stuck with an Aunt or Uncle that voted Brexit or thinks Nigel Farage deserves that knighthood? Deconstructing that awkward thing of dealing with relatives with antiquated views could have been very interesting.
But the episode didn't do that. The Bradley Doctor doesn't go on a journey where he learns his views are wrong. He shuts up when he learns Bill sups from the furry cup, but he seems to cheerfully go to his death thinking women should do the cleaning (and Polly having to do domestic stuff comes from Troughton, where she had to make the coffee. Once. Which she then used to kill Cybermen as it was Nescafe Gold Blend) and are very brittle things.
Worse than that, the 12th Doctor doesn't actually make any arguments against the sexism. He just keeps pulling sitcom "What are you liiiiiiiiiiiiike!" faces (oddly ibncluding when his counterpart is quite reasonably explaining to a First World War soldier that men can be nurses) and going "You can't say that!" without ever coming up with any reason why he shouldn't.
Compared that to the actual Hartnell era where whenever he went to far in his behaviour his companions would completely rip him apart (Barbara in the Edge of Destruction, Steven in the Massacre and so on).
We're also clearly supposed to still like the First Doctor, even though someone who kept saying things like that after being repeatedly asked not to is just a dick.
It feels as if Moffat is so annoyed at the accusations of sexism that are frequently aimed at him (somewhat unfairly IMHO, though I've not seen Sherlock which apparently has some hum-dinger moments in it) that he's snapped and started screaming "BUT LOOK AT THE OLD SHOW!!!!!"
All he's really leaving himself open to is not having any room to complain come the 2047 episode where the recast 11th Doctor barges in going "Ohhh, very clean Tardis. I guess you've no bad girls with sexy bums about the place then! Now, find me a lesbian to kiss against her will until she has to slap me". It certainly feels a bit rich for the writer who shouted "YOU WILL BE ERASED FROM DOCTOR WHO" at Caroline Skinner to take an era of the show kickstarted by Verity Lambert to task for its sexism.
Now, compare all this to a film I'm planning to watch tonight as a contrast: Star Trek VI. Which also uses 60's TV icons to explore the inherent bigotry of that generation.
Now, as I've learnt from this forum, there are Star Trek fans who loath that film (as did Gene Rodenberry) because Kirk and company were never that racist towards Klingons. And there's a point there, even in the films Kirk was prepared to offer his hand to rescue the Klingon bastard who killed his son and the previous movie ended with everyone getting blind drunk with a Klingon crew.
But it works because the film has a point to make, about how even generally good people can be bigoted without even realising it because of the culture they grew up in and it can be hard for them to adapt as society changes around them. But it is possible to change and become a better person if you keep open to new ideas no matter how old you get. No one has to be a dinosaur.
Next to that you've got "Women eh! Like glass. Just ignore the fact that I don't actually know I'm turning in to Patrick Troughton yet and by the rules of regeneration this episode is working to for all I know I could be about to become a woman so my attitude to women literally makes no sense whatsoever" and it's just oh **** off.