1. This iteration of the Cybermen was actually kind of intimidating.
Gaiman’s version of the Cybermen, which were very Borg-like, managed to make them a villain of note again. They were extra fast, extra dexterous (to the point of detachable operation in some very cool scenes), and extra adaptable. Watching one Cyberman get hit with an attack, process said attack, and then build and issue an upgrade to its entire fleet so it could be moving again in a few scant seconds was amazing. It gave the Cybermen a weight and credibility that had been slipping away that last few times we’d seen them. It was totally plausible that they were an opponent so fearsome that they had nearly wiped out the human empire before they had been stopped at a great cost. It made sense that humans had been conditioned to respond to the Cybermen with drastic actions, including imploding a planet, several galaxies if they have to. The ever-ominous single living Cybermite at the end of the episode promises the return of an ever-learning, ever-changing villain that will hopefully be a real challenge for the Doctor.
2. Mr. Clever, aka Evil Doctor, was great to watch in action.
There’s nothing more fun than watching the Doctor trying to out-crazy himself. It was great in the Dream Lord episode (“Amy’s Choice”), and it was wonderful as Mr. Clever (the Cybermen’s overarching consciousness/programming), which had uploaded itself via Cybermites into the Doctor’s brain. It was really interesting to see a villain typically very cold filter its thoughts and actions through the Doctor’s emotions. It was a nice reflection to see the Doctor through, because it exposed what we already knew but rarely see. Wrath, hubris, and ambition are all things the Doctor is very, very intimate and comfortable with, and they’re always bubbling just under his surface.
3. Clara got some great moments this episode.
Finally given some responsibility, Clara holds her own against a military leader, an army of Cybermen, and Mr. Clever, all without much of the Doctor’s help (he was busy fighting his own very important battle). We finally saw a little of Dalek Oswin come out in her. She was confident and decisive, undeniably clever this episode. But the pièce de résistance was Clara smacking the shit out the Doctor when he tried to tell her about his feelings for her. Her reasoning was perfect: “Even if you felt that way, you’d never talk about it” — a pattern that is tragically accurate and the recognition of which puts more evidence in the “Clara is some iteration of Rose and the Bad Wolf” theory.
4. Warwick Davis stole the episode.
Warwick Davis was such a treat in this episode. He did a lot of heavy lifting in terms of the Cyber Wars exposition and added the perfect touch of human element that “made you feel bad for the guy who had to push the button.” Not an unfamiliar feeling for Doctor Who fans, caring for a character who has destroyed entire civilizations, but again a wonderful, softer way to reflect on exactly what type of person we’re dealing with. The Doctor might have the tendencies and talent for world domination if he was so inclined, but the man isn’t exempt from the burden of hard choices, and what makes him special is that he feels the weight of these choices all the time, every day. Porridge, like the Doctor, runs for a while from his problems, but at the end of the episode returns to his rightful place as emperor after saving the day and knowing that he can make the hard choice again if he has to. Hopefully, that’s a neat bit of foreshadowing, and we can look forward to a season finale that at least hints at the fact that the Doctor might be able to stop running soon — maybe even get some closure on his tragic part in ending the Time War.
Side note: Clara totally should have married Porridge; he was wonderful.