I think that this is one of my favorite Hartnell stories that I have seen so far. I felt that it did a great job of making the Doctor and companions seem different from each other, as we see Barbara struggle with the proper etiquette for a time traveler, while the Doctor seems to tread in Aztec society with greater ease. I think that this is an excellent showpiece for Barbara, as the story has her in an interesting position where she has a great deal of agency as the supposed incarnation of a goddess. My mother, who is not particularly familiar with this era of Doctor Who, said that she liked Barbara purely based on seeing a few scenes in this serial.
The agency and authority that Barbara displays is an intriguing contrast with the fact that she is an unwitting time traveler at the mercy of a mysterious and sometimes apathetic man known as the Doctor. Perhaps Susan’s plot thread, though not as developed, puts her in the opposite position, as she is used to spending time in societies in which she has more agency, but is expected to acquiesce to marry a man she does not love. Ian’s hand-to-hand combat was also exciting, though I did find it slightly tedious that he was framed for murder again, as Ian was framed for murder in the previous serial.

It is also interesting that this is a story in which our heroes do not get to win the day. This does not happen particularly often in Doctor Who, so it is interesting that we establish our heroes as fallible. I think establishing the fallibility of the heroes, the Doctor especially, is something that the First Doctor Era of the show does especially well. Without this framework, The Aztecs would not work as well as a story.
Overall, I was impressed by this serial, especially considering that I did not find John Lucarotti’s Marco Polo to be nearly as enjoyable. A well-earned 8/10.