I can easily rewatch Spock's Brain even though I find it baaaaaad, but Plato's Stepchildren I skip every time. It's just awful and cringeworthy and I am sure I hated it even when I saw it at the age of 10.
I hated it...but, I will say it has its unintentional comedic moments -- starting with the Kirk slap-a-thon onward...
But, who's kidding who? It's a terrible episode and I resist all efforts to make it seem like a great episode just because it has the "first interracial kiss".
Whenever people bring that up, I always say "Yeah, but it also has Kirk pretending to be a horse with a midget riding his back...and Kirk and Spock dancing around like fairies!".