Obviously it's a landmark story, being the intro of the Cybermen and Hartnell's last episode. These things lend it some points at a base level, but what about the story itself? and I think it's probably one of the best use of Cybermen in the show purely by virtue of focusing some on their origin story. Ultimately they still kinda amount to generic baddies but there's something about the way they used to be human that comes through in their design and the way they talk in this episode, that never quite feels the same in later appearances... well, until 2017, but that's another story.

What else to say? The American guy is funny, Hartnell's great as always especially near the end, and this is probably Ben's best episode as he gets a chance to take down the Cybermen. We even see a bit of his softer side when he shows a moment of upset after killing that one Cyberman. (meanwhile Polly's reduced to the one who makes the coffee, but that's the 60s for you.)

I did find the actual solution to the invasion kind of disappointing, where they just have to wait til Mondas takes too much energy and everything gets destroyed – the Cybermen's plan was always doomed to fail. You could make a case that it's trying to say something about the Cybermen's brute resolution and lack of humanity, but in the episode itself it just feels lazy. Still, we do get a more proper climax with Ben using radioactivity against the Cybermen, which helps.

This is perhaps a more notable serial for its place in the show's history than its actual plot, but I do think there's things to enjoy in it as a story, even if it never quite rises above the ranks of other "fairly good" stories. Also, props to Planet 55 for what I think is probably some of the best animation of any missing episode in part 4!