Some nice touches in this one, with the Doctor and companions landing right in the middle of the Aztec civilization. Barbara gets taken for a reincarnation of a revered high preistess, and starts to declare human sacrifice is unpleasing for the gods. There are power struggles, and the Doctor insisting you cannot and should not interfere with history, and reasonably good set design for such a stagebound, low-budget production, and the lead characters are mostly fine, though some are quite wooden. I also like the part where the Doctor inadvertently gets engaged when he shares drinking cocoa with a woman taken with him, and he indeed feels affection and admiration for her. The final shots in the Aztec kingdom have him put a gift from her down just outside the Tardis, but then pocketing it at the last second before going into the Tardis and leaving.
Rating: Good, 6/10