The cheese factor is very high in this one, but that's part of what I find attractive in the original series.
This episode waxes philosophical about war--a fairly common theme on the original series, which was made all the more poignant because it aired smack dab in the middle of the Cold War. Like usual, Gene Roddenberry (along with story writer Judd Crucis) has apt things to say about war and the necessity of taking up arms should an opposing group choose to do the same. More strongly, and this is especially relevant in retrospect, here in the early 21st Century, the crux of the episode is really superpowers creating/supporting/funding wars among third world peoples.
But as good as it can get on philosophical content, Star Trek excels because of its peculiar mixture of often cheesy or at least cheesily played elements, and this episode has that in spades. Not one, but two principal cast members almost die as they visit that same rocky scrub brush location in California again that always stands for some different planet. Another principle cast member is injured. This time they meet up with some ridiculously wigged primitive folks--one of whom Captain Kirk became friendly with on his first mission to another planet over a decade before. While there, they meet and fight with a ridiculously costumed "mugato" (maybe the problem was that they forgot the traditional "Domo arigato, Mr. Mugato" greeting?), and a ridiculously hot and beautiful Nona (Nancy Kovack), a member of a "witch tribe". This latter fact leads to some romantic scenes for Kirk, of course, and even a pretty racy (for prime time television in 1968) "healing" scene. This episode is also the source of a very humorous way of waking Vulcans out of a particular kind of "meditative" state.