Yeah, okay, there's oxygen-deprived zombies in robot suits, but the actual villain of this episode is brainless, heartless capitalism. It's incredibly easy to believe that if/when we as a species make it to space, businesses will be there going "yeah but we can make money off of air, so we vented all the oxygen to keep prices competitive :D pay up or suffocate!" And then killing off employees when they become inefficient because workers who aren't productive are a waste of oxygen. "Business as usual."
Poor Bill. This was not an exciting and fun adventure for her. And the scene where she's exposed to the vacuum of space because her suit is malfunctioning was one of the most genuinely horrifying things I've ever seen on Doctor Who. Or television in general. And then her central nervous system is disabled. If she ever sleeps through the night again she's a stronger person than I would be.
Once Bill was affected I was kind of expecting it would turn out that none of the zombies was dead, just "disabled", but for dramatic purposes "Bill's suit was too low on power to administer a fatal dose" is a better ending.
I really enjoyed Bill and Nardole's dynamic. They seem to like but not totally understand each other, and it's great when they gang up on the Doctor ("you couldn't have just told us that?" "are you trying to scare us?!"). And the hug at the end was adorable ♥ (Also the nod to The Daleks in the beginning, with the fluid link. The Daleks already has a healthy dose of "the Doctor lies", I'm willing to accept another layer.)
And WHOA that ending. How long are they going to keep THAT in play? I hope for a good while for appropriate dramatic payoff, but oh man that's going to be tough storywise, since he's concealing it from Bill (and everyone else but Nardole, most likely). That's definitely upping the ante...