Eh...while it wasn't as predictable as I feared it would be, it still ultimately led to a reset button where no one but the heroes remember what happened. I hated that when it happened with "The Last of the Time Lords" and I hate it now. At least the whole "The Doctor is regenerating!" business was dealt with right away and it was the blatant misdirection that we all expected it to be, albeit the nature of the misdirection wasn't what I expected. That being said, I don't like the notion of push comes to shove, Bill will shoot The Doctor if she thinks he's gone bad.
The main highlight of the episode was Missy's first scene. The rapport between Capaldi and Gomez continues to be wonderful, even if I don't buy Missy's "I'm trying to change" act and I certainly don't buy her crocodile tears at the end. I did like her point about being good isn't an absolute and that The Doctor can't expect her to become his kind of good. I hope that theme is continued to be explored for the remainder of her appearances this season.
The only other major highlight was this line from Nardole: "Oh, well, that's not that weird. I once had an imaginary friend. He left me for someone else. Heh! I know, charming!"
The rest of the episode with the Monks was pretty pedestrian. Others seemed to enjoy the dystopia aspects, but I thought it was rather flat and uninspired. Plus, we never found out their motivation for world domination other than "because they could, so why not?"
The overall trilogy didn't really work for me. I loved "Extremis" and it was a solid set-up for the rest, but the following two episodes were a bust and the ideas felt half-baked. Especially disappointing with Toby Whitehouse because he's normally good to excellent. Makes me wonder what his episode was like before Moffat decided to forcibly merge the three episodes into a trilogy.
A minor pet peeve: I'm disappointed
Doctor Who repeated the claim that Thomas Edison invented the light bulb.
That was quite good, but I can't help feeling it got weaker the longer it went on. The world run by the Monks was interesting early on, I liked the idea of the memory act 1975 (or whatever it was) and the Doctor as mouthpiece for the Monks was a nice idea. I like as well the allusions to both the last series of Sherlock and (more pertinent from a Who standpoint) The Sea Devils, with the Doctor this time mesmerising (or un-mesmerising) his guards the same way the Master did back then.
I did like the allusions to The Third Doctor. This might have been just me, but the little key/lever that The Doctor turned before opening the Vault felt like a callback to The Third Doctor as well.
Why did the Doctor fake a regeneration? Who was that for? Bill doesn't know about regenerations and everyone else in the room knew the Doctor was fooling so really it was there for the viewers, which kinda pulled me out of things.
Yeah, that bothered me as well. The whole purpose of that bit felt like "Let's create a fake regeneration so we can throw it into the trailer and mess with fans!"
Also the resolution was a bit weak to say the least. So Bill didn't end up a husk after all?
That really bugged me. What was the point of building up the tension about Bill becoming brain dead if then she's going to be fine...without any explanation for why she was fine?! Because of her memory of her mum? What tosh.
Massive overblown monk threat!!!! Oh no, all sorted in ten minutes by someone thinking of their mum while the Doctor shouts a meaningless 'explanation' over the top. All that setup for that?
That whole sequence felt like Davies at his bombastic worst.