I hated The Way to Eden while watching it, but I did enjoy the end where the hippie leaders die and the rest become disillusioned. Bad episode, great message.
I just can't get past the horsie scene in Plato's Stepchildren. It made me cringe more than anything else I can remember. Even after all Will Shatner has done, he did not deserve that.
I agree with Way to Eden, a thoroughly annoying episode. At least Spock's Brain was pure camp.
I've never jived with that opinion of the "horsie" scene in Plato's Stepchildren, you're certainly not the first I've heard this from. I understandsome people hate things that make them cringe as a rule. However, it's a bit ironic that you feel bad for Shatner (an actor) for having to play a scene that was meant to show his humiliation, and he succeeded in that, but you just don't like the feeling. So he and the writers succeeded brilliantly in exactly what they were trying to do and you're penalizing them for it. Know what I'm saying?
The Alternative Factor was indeed confusing, and full of glaringly bad science, even for the 1960s. I just read on Wiki that it also played a role in bringing about the end of one of the Barrymore's acting careers, which is more interesting than the entire episode.