This is probably one of the best looking, greatly directed episodes this show has ever had (the final facedown with the army of Cybermen is so cool, the beginning with Bill holding the Doctor...).

The story is excellent, the sci fi stuff with the time dilation is so good, such a great concept and execution.

What else? Bill turning into a Cyberman and the whole scene when she realises the truth, Missy and the Master killing each other off when she is about to side with the Doctor, the Doctor himself having grown so much as a person since series 8... He is definitely a good man, he always was, he is The Doctor. This is the best finale for any Modern Doctor (the next one is more an epilogue in my mind, so this still counts). It would be the best but Androzani exists, they are both tied in my opinion.

This era is my favourite of the whole show, this rewatch has been amazing. I'm looking forward to rewatching 13's run, as I didn't enjoy it that much the first time. I'm going in with a positive attitude, I hope I change my mind a bit. Will post reviews of that in the future (at least with episodes that warrant one)