Oof, I'd meant to catch more of this series but have been whiffing on it, I guess. So, let's see...

• I thought it very interesting that Walker was (evidently) segregated from the rest of the actors, heightening his sense of alienation. And it shows! Pretty unusual though for TV, and AFAIK something only occasionally used in certain films. So-- definite credit to Walker and director Dobkin for being willing to carry through with that, altho of course, I suppose it might have been done under Roddenberry or other exec's order.
• Interesting how TOS (I don't think I need a spoiler for this) featured all-powerful beings several times, which later became kind of codified in TNG as the "Q." Now if that concept had been established from the start, would Charlie's people (and certain others) be explained as being Q? Actually, I prefer TOS's approach to all that, making it sort of organically mysterious from ep-to-ep who was being dealt with, exactly.
• I thought Grace Lee was rather ravishing here, did a great job, and had some pretty riveting interactions with Charlie. Btw, one thing I remember reading about her wig is that the 'checkerboard pattern' was a separate wig that was glued on to the first.
• Thinking about it a little more, TOS seems like it had an unusual number of situations in which the crew were mostly helpless against a far more powerful entity, testing the very fibre of their training and character. Now that's almost a routine format for TV and movies, but it seems to me like there's usually more of a back-and-forth balance across such media, whereas in TOS, it's almost a blueprint for 'how to stand up to a bully.'
• Btw, as fandom has introduced a certain amount of spam and unwanted extras over the years, there's now a cleaner way to display such content. I.e., just add "anti" in front "fandom" in the original link, and it will redirect to a new link.

EDIT!

• Also, I loved the lush, colorful lighting used in these early eps, which were used in the first half of season one IIRC. Together with the ever-amusing noises of the ships' systems, combined with the incredible little music snippets & interludes, it was almost like having an extra lead actor or two. But rather brilliantly, those things fully complimented the main human stars, and didn't take away anything, only complimenting what was already there.

Visual effects comparison of the original broadcast & the Remastered versions.

https://www.youtube.com/watch?v=SgnRZzvv0bA