I've often said that this is the only episode in Doctor Who's history that I think would be worthy of ending the show.

Do not get this story if you ever want to take the Cybermen seriously again because there is no way any other story they are in could ever compare to this one.

It is everything that one would want from a Cybermen origin story and is better than Genesis of the Daleks in my book. It single-handedly made the Mondasian Cybermen my favorite version of Cybermen. Their voices are just terrifying.

A thrilling and emotional tale that has you holding your breath the entire time.

And remember: "Daaaaaaaad? Daaaaaaaaaad? Daaaaaaaad?" one of most heartbreaking moments in Who history.

It has some good dialogue and the relationship between the Doctor and Clara is very good, but the plot is very thin, the villains, while I adore the design, are completely nonthreatening, and the ending is abysmal. At the end of the day, it's main purpose was to introduce the character of Ashildr, but it fails in that because instead of taking Ashildr and building a story around her, the writers took a filler episode and stuck Ashildr in it, meaning that it failed as both a standalone and as part of a greater story arc. Overall, not a terrible episode with some good moments, but it failed as a whole.

Had a few good ideas and a lot of bad ones