This review reportedly contains spoilers. I can handle the truth.
This was the only Star Trek movie from the original series that I saw as a kid. It left an impression on me and I remember it fondly and watching it today reaffirmed that fondness. Everything seemed to be clicking in this movie between the cast, the direction, the story and its execution. The first 15 minutes of the Enterprise crew in present day San Francisco is some of the best fish-out-of-water stuff you'll find in a movie anywhere.