The third in the series of Star Trek movies. I doubt that I will spoil anything for anyone to say that the whole point of the movie was to resurrect Spock. (He died in the last one.) Good points include James T. "Prime Directive My Ass" Kirk ignores direct orders once again and kicks some Klingon butt. Also this is the first time that fans got to see more than a short sequence with the new and improved Klingons that became standard in Star trek: The Next Generation.
Bad points include... The Plot or lack there of and wooden acting on the part of the usual offenders. Also there is some rather hoaky science, but that's par for the course in Star Trek or any other space opera.
It does set up a rather good movie though. Star Trek IV: The Voyage Home
Thanks to ithron for pointing out a mistake about the Klingons