Originally Posted by samwiseb
Easily tied with II as my personal favorite Trek movie. In so many ways, it's just not the kind of movie either the TNG producers or Team Abrams would ever make. This one was my first real introduction to Trek at age 12. I also maintain that it 'looks' nicest of the TOS films, though you wouldn't call it epic in either the visual or the operatic sense of the word.
I think you are onto something here. It is no epic movie, it has no effects festivals, it's story is pretty straightforward, so what is so great about it? It is not generic, it is just itself, not a copy of anything or an execution of a well-working formula. Furthermore the humour feels natural and is embedded into the very playful* and light-hearted way of the movie whereas the humour in a movie like INS (and I may say this because I am one of the few folks who loves INS) feels superimposed.
* - To say it with Oscar Wilde: "In matters of great importance, style and not sincerity is the vital thing." Kirk's playfulness has infected everyone and everything in this movie. Which is true to a certain degree for all TOS movies, the playfulness and the atmosphere of living classics are their most important assets in my opinion.