Every movie series has its lousiest production, and for Star Trek, this is it. I think William Shatner did a lot of good for the Franchise, when it came to his acting. Unfortunately this was the one movie he was allowed to direct. If he was going for bringing back the extreme campiness of the original series "Bravo!". The special affects in most cases were terrible. Acting was spotty, and the story was trying to be epic without actually succeeding. He put Chekov and Sulu in situations similar to the original series where they comically play off each other, like they were young men again. The only problem is they're pushing 40 or 50 years in the film. There playful college days were over a long time ago. It just seemed a bit weird to me. The comedy in ST 4 was so much better.
Despite all this, the movie is a romp. If you're a fan, it is worth seeing once. Worth seeing a second time to make fun of it as you go through the movie. this one is pure 'B' material