I've come to the realisation that I don't enjoy Terry Nation scripts. Both this story and The Daleks have a potentially interesting concept and potentially interesting side characters, but get bogged down with useless meandering.

Setting aside the fact that a society completely controlled by a machine's idea of right and wrong is dystopian as all hell, made more so by the person in charge forcing the main characters to support it against their will, and the only comment on that being a single line spoken by the Doctor at the very end of the serial, it's just...not very interesting. We could have had actual commentary, but instead this setting is a backdrop to "basic evil bad guys" and a bookend to a fairly simple treasure hunt.

Removing the titular character from a third of the story was a bad choice. It doesn't help that the side characters are fairly flat. I like that Barbara has more to do in this story, but Suzan is once again relegated to screaming for cliffhangers, which is especially noticeable after she played a more major role in Marco Polo.

The first two planets they visited had interesting concepts at their cores, something that a different story would have taken time to explore. The last two planets lost steam completely, being fairly generic "ice planet #n" and "tribunal", both of which have been done to death.