Nimoy directs the comedy in a loose, relaxed, almost sketch-like manner, but when the film moves into its multiple-cliffhanger climax, he's still able to generate some genuine dash and tension. The only drawback is that the Enterprise gang is starting to look a little long in the tooth for such strenuous action.

Dave Kehr

Chicago Tribune

William Shatner's Kirk is less stoic here than in III--he's pleasantly daffy. The others in the crew also have an easy, parodistic tone. But the picture doesn't have much beyond the interplay among them and the jokey scenes in San Francisco.

The ecological message is commendable, and there are some amusing situations with the space travelers in contemporary scenes. Nimoy's direction keeps a lively pace and the special effects are state of the art, as always. [08 Jan 1987]