I just saw "City on the Edge of Forever", and I've done some digging around the internet, so I know something of the background. His initial draft is not as good as the final product, but, then again, I only SAW the final product. That said, "City" is a good SF episode, because it has a SF element - time travel - without which the plot would have failed. As Heinlein said, that element has to be crucial to the story or it would not be good SF.
As an aside, he sued James Cameron because Cameron allegedly stole the idea for Terminator from two of Ellison's TV episodes. Actually, "City's" storyline would be closer to Terminator than those episodes, but, of course, Ellison never owned the rights to "City".
I'm doing a SF series, as some of you know, and I've written down quite a bit in terms of my series bible and draft episodes. I'm wondering if I should read more on how "City" was produced, the trials and tribulations. Does anyone know of any works on the making of that episode?