Search for Spock gets a bad wrap, but it's a film that's entertaining, sentimental, and always better than I remember it. But it just doesn't stand alone as a film on its own merits, which is one of the reasons I think it isn't as highly praised or well remembered as perhaps it should be.
The second installment of what is now popularly called "The Star Trek Trilogy," III mostly concerns itself with the aftermath of II, while bringing things back to the status quo in time for IV. So, for the most part, it's a transitional film, and watching the previous film is something of a prerequisite. If you aren't invested in the character of Spock, this film will mean very little to you, and since Spock only appears in the last scene (more or less), this isn't a good jumping on point for new viewers. And, frankly, the lack of Spock does hurt the film, since he was such an integral part of the success of the series. Luckilly, everybody talks about him so he's never far from the core of the story.
What holds this film together is the clever storyline, the exciting action sequencs, and the brilliant direction of Leonard Nimoy that holds it all together. Nimoy is my pick for the best Trek director of all time. He has the talent and visual inventiveness of Nick Meyer, but more restraint and love for logic that keeps the story from going off the rails, the way Khan did constantly, in my opinion. Nimoy is a talented director who kept the film focused, well paced, and on tone. I can't find anything worth nit picking about this movie.
This film also has the best villain from the film series, which nobody but me will admit. Khan was great, but he was a cartoon with cartoonish motives and nothing original or clever to say. He was ripped off from Ahab and most of his dialogue was dipped off from Moby Dick. Not a great villain, in my eyes. But Christopher Lloyd's Kruge is awesome. He's almost like a darker version of Kirk. Even his name sounds similar. There isn't one moment in this film where Kruge doesn't do the logical, smart, evil thing. His fight with Kirk in the finale is also the best fight scene in the entire series.
Also, Robin Curtis was a better Saavik than Kirstie Alley. But that's just my personal opinion. As an actress, she seemed to have a better understanding of what being a Vulcan actually means. Or maybe it was just because Nimoy was directing, so she had that kind of guidance to work from. Either way, she's my favorite Saavik, and since she was in two films while Alley was only in one, she also wins by default anyway.
So Star Trek III, in its own way, is a great film and a worthy entry into the series. It's a great odd numbered film too, which helps put the lie to that old canard that the odd films are all worthless. What this film isn't, however, is emotionally satisfying when taken comepletely on its own. It's a film that exists simply to bring Spock back to the cast, and has little to no back story or expository explanations about their mission, Starfleet, or the Trek universe at large. But that's as it should be. The rebirth of Spock had to be intrinsically linked to the death of Spock, to give it that much more power and emotion. The final scene, which is one of my all time favorites from any movie, echoes scenes and dialogue from the previous film to such an extent that the emotional payoff can only exist had you seen Khan.
So if you're a Trekkie, give it another look. It's a good film. If you're not, watch the entire trilogy. They're awesome.