Trek III wasn't my first Trek experience. I had grown up watching Next Generation, so I was familiar with Trek. Then one day my mom comes home with these Trek movies for my sister and I. We watched the first one, not to thrilled, in fact I remember mocking it a bit.
Then she showed us the second one.
Supposedly I had watched TOS as a toddler with my parents, can't remember it, so the Trek movies were really my first experience with the original cast. Within two movies I was in love with the cast, particularly Spock. And then I watched him die in TWOK. I was devastated, crying at the end of the movie. My sister and I were very upset, so our mother told us that there was a third movie. We begged her to rent it, and we all went to the movie store that very night to rent it.
The next night we watched it. Not the very best, but still a solid film, and they brought back Spock. I was ecstatic and went on to watch the other films. While the third film wasn't my first Trek experience, it still was a very important and memorable part of my first TOS experience.
To this day I'm rather fond of watching II, III and IV back to back.