Well, here it is, the grand finale of the Moffat Era. And, well...either typically or tragically, it seems to be divisive. I will say that I'm on the side that liked it.
From the get-go, if anyone does plan on watching it, do not expect a high stakes final episode like "The End of Time" or "The Time of the Doctor." If you want that part, I'd say watch the Series 10 finale. This feels more like an epilogue, which means it's somewhat introspective and very fanwanky (in the sense that it plays to nostalgia). There's musical cues and references to past galore, and I've heard tracks that haven't been used since the early RTD era. It makes sense, especially since I've heard that Murray Gold, the fella who's been responsible for NuWho's music since the beginning, is also leaving.
Going to be honest, the meat of the plot wasn't very substantive, it feels more like a tool to help the Doctor come to terms with regeneration. Rather than a final enemy or danger. Like I said, don't expect the episode to be as high stakes as 11 and 10s finales. But at the same time, I don't think it's really needed. Moffat never really had any grand overarching plotlines with 12, compared to stuff like the Trenzalore or Silence arcs. As such, I don't think there really needed to be any resolution to past plotlines, only thing needing resolving was the Doctor coming to terms with regenerating.
I liked the 1st Doctor overall, but they really stretched out making fun of 1960s attitudes. It got cringeworthy at points. Likewise, I found Bill's part in the story to be a little unnecessary, and I'd rather she just appeared at the end to see the 12th Doctor off, as Nardole and Clara did. Those points aside, I did like the references made to things like Rusty, or the Doctor's previous feats.
As for the regeneration. It was good. I was worried that Moffat would take too much inspiration from RTD's send off and have the Doctor be a bit clingy at the end, as 10 was. And that whole sequence with him visiting past companions. That's not to say Moffat doesn't do anything similar, we have goodbyes with 12's companions, but I felt it was more to help 12 be at peace and less him doing it for the "reward," for want of a better word. 12 seems content at the end, and much like 11, goes off with a speech that feels like a message to fans to accept the new. And then the change happened. It's probably one of the better regeneration effects, don't think it beats 9->10, but better than the ones we've had in recent years. AND DAMN IT. I knew it was going to happen, but I am really going to miss 12's TARDIS. I really hope Chibnall takes cues from it for the next design.
As for 13, it's interesting to note that they didn't have her comment on her appearance. The only thing she said was "Oh, brilliant," in a very 10ish way. I'm hoping it's not going to entirely be the case, as while I was expecting a more 10 like Doctor, especially after 12's abrasiveness, I don't want her to be a female version of 10. She needs to be her own Doctor, take inspiration from the past, but don't make her a genderswapped version of a past version. Obviously, this is going off very little, and I hope she does grow into her own incarnation. But at the same time, I am a little apprehensive given 10's popularity and the possibility of bowing to pressure.
And so, we fall into a new era of Doctor Who. From what I've read, Chibnall wrote the post-regen scene, much like how Moffat wrote 11's post-regen. And looking at it, it seems promising. Of course, we'll have to wait for Series 11 to see how it turns out proper. I've no doubt that we'll be seeing changes soon, such as a new logo at some point. But to Moffat, for all his ups and downs, I thank him for running Doctor Who over my teenage and early adult years. He's had his bad episodes, but he's given some classic ones. My thanks to Capaldi for being such a wonderful Doctor. It's going to take an effort to dethrone him as my favourite.