The MINIATURE fx from the first few seasons don't hold up well,
They look like 1985 TZ eps, which for me is worse than most TOS fx in lighting and presence.
What are TZ eps? Do you have a Memory Alpha URL link?
TWILIGHT ZONE. Rob Legato, the vfx guy on TNG, was doing similar stuff for TZ a couple years earlier, compositing film elements on video, along with what looks like chromakey stuff.
I don't have to go to TREKCORE or anyplace else to remember how bad some of these shots are. Just look at the end of LAST OUTPOST for the two xmas ornament lookin' ships in front of the planet. Pretty much all the 2ft ship shots look rough to me. A lot of that is the 30fps instead of 24, which always makes it harder to do scale stuff credibly, because the higher frame rate gives it more of a video like presence (if you have ever seen the old movie OKLAHOMA, you might know what I mean ... it was filmed and shown at 30fps, and it has this awful unfilmlike feel.
There was SOME really good stuff. That terrible time squared episode had some really nice work in it that should have been in a better episode.