Apologies for the hijack.
There are many ways to assess TOS episodes. For me, one of the more important ones is visual effects; in particular, starships maneuvering through space and firing beams. “Elaan of Troyius” has more such action than (almost?) any other TOS episode. Along with miscellaneous other efx, it also has the greatest transporter effect of any episode, a close-up with (what looks like) 4 or 5 glitter passes on Ms. Nuyen as she beams down.
Another important TOS consideration is of course space babeage. Ms. Nuyen looks great, has some of the best hair of the series, is awesomely costumed (a series hallmark) and makes a superb “space bitch.” It’s easily the best performance of hers I’ve ever seen…and I’ve seen at least five of her 63 credits listed on IMDB.
While Mr. Shatner, et al are in their usual fine form, the stand-out performance in the supporting cast comes from creepy Jay Robinson. It was one of his first credits following a drug bust in the late ‘50s that effectively ended his movie career for several years. Admittedly, he complains a lot in the episode, yet somehow never comes off as too obnoxiously whiny (e.g., imagine Jonathan Harris in the role).
Plot-wise, the episode weaves action, romance, humor, mystery and political intrigue in the best TOS manner. There is a palpable sense of dramatic escalation and tension in the climactic space battle. I think one of the more subtle reasons these sequences work as well as they do is the music. I am sure the sample used was reused in other episodes, but it was not as overused as much as certain other music samples associated with the series. It is also unusually well edited/integrated into the episode.
The biggest criticism I can make of the episode is that when Kirk says “fire phasers,” the stock shot which follows has the Enterprise firing photon torpedoes (note that this mistake is recreated in the “remastered” version of the episode with CG torpedoes). It is annoying. I hope whoever was responsible for it got a lengthy session in the Agony Booth.
Comparison to other alleged “best TOS episode” candidates is revealing. “City on the Edge…” has Joan Collins in soft focus, and perhaps a greater dramatic impact, but it can’t compete in terms of visual efx, action or tension; “Amok Time” has even fewer efx and too much lame-ass Vulcan ritual (and Dr McCoy’s a cheater…I hate cheaters). “…Tribbles” is perhaps funnier, but comes up well short in terms of space action and babeage.
I have never understood why this episode is not more highly regarded. I know I have read some criticisms, but I don’t recall what they were. I obviously did not find them as compelling as the case for regarding “Elaan of Troyius” as the “best TOS episode.”