I saw many of the original series episodes when they came out in 1968 and 1969 -- but I was only six years old at the time! At that point I only liked the episodes where Kirk got into a lot of fistfights and fired his phaser. And especially the episodes where the Enterprise fired all its phasers at another ship!
Fifty years later . . .
This episode, which I hardly noticed as a little kid, is now a favorite. It's haunting, tragic, deeply romantic, dream like, and sensual. The idea that god like aliens long to be human, to have all the feelings and emotions we take for granted, is deeply inspiring. It's all the more poignant because they speak to us in the voices of people we already love, like Kirk and Spock and the incomparably lovely Ann Mulhall. I loved how the "temptation" of Thelessa was so Biblical, with the suave Henoch in the role of the serpent.
People joke about the plot, but from an acting perspective it must have been so liberating for William Shatner and Leonard Nimoy to take on these "dual" roles as aliens inhabiting the bodies of Kirk and Spock. Shatner gets to play a man who is quite different from James T. Kirk. Sargon is a great leader, a hero, but he's no playboy. He's dignified and caring and his scenes with his lost love are unbelievably touching. And for Nimoy to be able to step out from behind Spocks' shadow and play a truly Satanic villain must have been a real thrill. I think Henoch is one of the best Original Series villains and I think Leonard Nimoy deserves a lot of credit for bringing him to life!
Private joke: when Sargon talks about spending thousands of years searching the universe for passing ships to help, he says something like, "Always waiting, always probing, probing, waiting, probing." I wanted him to go the full Buddy Holly and say he was "crying, waiting, hoping" instead!