So, it turns out that everything we had seen and heard about this episode before it actually became available was a classic case of deliberate misdirection. We were led to believe that this final episode of the ninth season of Doctor Who would be tense and exciting - and, that it would concern itself primarily with the Doctor's revenge against his own people. Because, of course, that was the big revelation that we ended the previous episode with - that the ones who had worked so hard to lure the Doctor into such an elaborate trap were the Doctor's fellow Time Lords.
By the time that the Doctor had been able to escape from that strange prison (which, it turned out, existed within the Confession Dial that had been featured throughout the season), he had clearly seemed to be angry enough to turn on his own people. Even the promotional trailer for this episode had been cut together in a way that made it look as though this was exactly how things were going to play out.
Clara's death, a couple of episode ago, had seemed tragic and pointless - something about which the Doctor, clearly, agreed. But, it had also felt very final. The Doctor's experience in his strange prison, in the previous episode, had even contained elements of the Doctor seeming to come to terms with the fact that she was truly gone. So, with that in mind, it was certainly strange for this episode to open with the Doctor encountering Clara in an American diner. How was this even possible? Well, obviously, that was going to be revealed later.
Back on Gallifrey, though, the Time Lord's are still concerned about the existence of the Hybrid - a creature destined to destroy Gallifrey, which was first mentioned by Davros back in the season's first episode. The Time Lord's are convinced that the Doctor knows who, or what, the Hybrid actually is - and, in fact, had arranged to trap the Doctor specifically to uncover what he knew. And, now that he is free, they are still adamant that he shares what he knows.
But, as we soon learn, the Doctor doesn't actually know anything about the Hybrid, and never has. In fact, all of this had just been part of the Doctor's own elaborate ploy - one intended to get him access to a rare piece of Time Lord technology that would allow him to speak to Clara in the moment just before her death. It's only supposed to used temporarily - a slight bending of the usual rules that creates an opportunity for a final conversation. Of course, the Doctor intends to find a way to make it permanent - and, his efforts to do so lead the Doctor and Clara to steal another TARDIS and flee to the very final moments of the universe. And, there, they encounter 'Me' (Maisie Williams) - still very much alive, and enjoying the sadly beautiful spectacle of watching stars die.
So, rather than being about the Doctor's anger, and his desire for revenge, this final episode is actually all about Clara - and, about giving her a much more fitting send-off then the somewhat abrupt death she had a couple of episodes ago. It is, also, an episode set on doing the same for Ashildr/'Me' - an increasingly fascinating character who was one of the clear high-lights of this season, for me. There is a resolution, of sorts, to the season's arc concerning the Hybrid - though, much like with everything else in this episode, it's not quite what you would expect. There is, in fact, an amusing conversation between the Doctor and 'Me', where each suggests that the other might be the Hybrid - only for the truth to turn out to be something else, entirely.
This is a quiet, and very somber, final episode - and, it's really much better for it. Those tense scenes between the Doctor and his fellow Time Lords from early in the episode were entertaining, of course - but, it is the quiet moments between the Doctor, Clara, and 'Me' that are the true high-lights.
Honestly, the only potential issue with all of this would be that, in order to feel any sort of personal investment, you really have to be fully on-board with the idea that Clara is actually, and genuinely, so important to the Doctor that he is willing to go to such extreme lengths to get her back. Essentially, what you're being asked to accept is that Clara is, basically, the most important companion that the Doctor has ever had - because, we've already seen that he was never willing to go this far for any of his previous ones. As someone who has struggled with Clara, and the way she has been characterised, over the past few seasons, I do have to admit that I wasn't quite as emotionally invested as I probably should have been. But, I also have to admit that Peter Capaldi and Jenna Coleman still managed to win me over, somewhat, with their fantastic performances. Maisie Williams's own part in this episode was, comparatively, fairly small. But, that brief glimpse we got at someone who, by that point, was ancient even by the Doctor's standards was fascinating - and, she definitely played it very well.
Any other issues I could point toward are, really, just a result of my own personal preferences. I had been anticipating that Missy would appear once more, at least, before the end of the season - so, I do have to admit that I was a little disappointed to learn that that wasn't going to happen. But, I'm sure she will appear next season. Also, I would have liked to have seen more of Gallifrey, and the Doctor's fellow Time Lords. Having them return so suddenly felt like a fairly big development - but, then, they went on to not actually be all that important to the story being told. But, once again, maybe that will change next season.
The main point, here, is that this was a very impressive end to a very impressive season - and, a significant improvement over a previous season that had left me feeling, mostly, fairly ambivalent about the series, as a whole. This time last year, I wasn't even entirely certain I intended to continue with Doctor Who - but, now, I feel like I am genuinely looking forward to seeing how things develop in the future.