Great episode.
The idea of Kirk and Spock alone together on a planet fighting a guerilla war against the Klingons is a lot of fun. The final twist at the end, with the Organians deciding to use their god-like powers, turns it into an interesting bit of SF.
The story doesn’t quite add up, as surely the Organians would be able to see where everything is going and try to cut off the violence before it escalated. Still, this is a far better version of the old ‘there are strange things out there, be careful what you poke’ SF trope than Where No Man Goes Before.
Great trek moment: The first appearance of the Klingons, obviously. A great writing job, as the seeds for hundreds of stories down the year are planted very quickly.
26 down, 711 to go.