The Enemy of the World could've scored higher, were it not for the fact that a core part of the plot is Patrick Troughton in brownface doing a fake Mexican accent.

It's shot, directed, and paced well. The world is fascinating and the side characters are interesting (we even have a black character with her own motivations and plot relevance, which is a miracle for 60s Who, even if she does die in ep4). Troughton plays it well, with the Doctor-as-Salamander and Salamander-as-the-Doctor and more layers of subterfuge beside, it's just disappointing (to say through least), that Salamander is the way he is