This is widely considered to be the best Star Trek movie ever, and there are few good arguments against that assertion. It combines a compelling storyline with good dialog, a bit of overacting (but tolerable), fantastic special effects, and Ricardo Montalban's pecks.
The idea of taking a storyline from an old Star Trek episode and extending is was a brilliant one. Space Seed was a completely forgettable episode from the first season that really seemed like it would have been best left untouched. But this movie takes the basics established in that simple beginning and expands deeply. As a result, the storyline surrounding Project Genesis is actually just background to the true story of revenge.
It's nice to see Kirstie Alley settling in as recurring Vulcan character Saavik. We can rely on her and Spock to give the much-needed exposition where applicable. The two of them form a good team of mentor and student to the human condition.
Ricardo relishes his role pretty substantially, and he tends to overact even more than Shatner does, but his character is supposed to be an over-the-top narcissist and a very, very dramatic person. As he feels his place in history would be more significant than anyone else - past or future - he carries with him a sphere of self-importance and power that drips off the screen. It's impressive for the amount of time he is on screen, but any more would have strained credulity.
The usual cast does the usual job, and it's not bad at all. Scotty mugs for the camera a bit too much, Chekov's Russian accent is horrific but endearing, Sulu's voice has more gravitas than it deserves, and pretty much everyone else does their roles well enough.
The annoying uniforms from the first movie are gone. This movie introduces the winter look. I'm not sure what has happened to the environmental controls on the Enterprise, but the layered turtleneck look seems a bit much. Maybe you want to go ahead and turn up the heat if everyone has to wear big, bulky clothes to be comfortable. I mean, look at the Defiant! Ricardo doesn't even wear a shirt.
The storyline is great
The dialogue is good
The acting is good
The direction is spectacular
The special effects are impressive
5/5