Rosenman's score is not terribly popular for some reason, his jaunty main theme deemed far too light weight for a Star Trek film, but in fairness, the tone is just about right. The film was more light hearted than any of the others and the time travelling, fish out of water plot couldn't really be anything but a little humorous. It is admittedly similar to his theme for the animated Lord of the Rings, but not to any great detriment. The rest of the score is somewhat more incidental than the other Trek films, generally backing the handful of more dramatic moments. However, the amusing Russian tinge of the sprightly Chekov's Run is a nice counterfoil as is the equally comedic Hospital Chase. The action is scored with many of Rosenman's trademark musical pyramids as instruments are stacked on top of each other to quite unsettling effect. The Whaler is perhaps the highlight with plenty of tense brass writing and a more dramatic use for the main theme. Rosenman also concocts some splendidly creepy music for The Probe and I suspect given a more serious Star Trek film would do a fine job.
Most of the cues are fairly short, but the longest, The Crash Whale Fugue is unfortunately somewhat aimless. The brief run time of the other cues prevents them losing direction, but with this longer passage, Rosenman seems to run out of steam. The two tracks performed by the Yellowjackets are hardly pop classics and certainly don't do much to enhance the flow of the music. Home Again makes great use of both the original Courage fanfare as well as a brief snippet of his original theme before launching into a reprise of the main theme and his elegant and quite lovely waltz theme for the whales. I don't understand why the score upset so many people as it's terrific in the film and has plenty of great moments on CD. It's far from the best Star Trek score, but it was never going to be given the nature and tone of the film, but for all that it's good fun and a worthy addition to the series.
Rating ~ 
Total Time ~ 38:40