An excerpt:
Thank goodness DeForest Kelley is in this movie, because it would be unbearable otherwise. His acid tongue and snide remarks are the only relief from the endless stilted line readings. With Spock, this works, as he’s going for totally emotionless, but Nimoy also doesn’t stand out very much because everyone else sounds like that, too. Bits of personality occasionally bleed through in the regulars, but the secondary actors—from the Epsilon 9 crew to DiFalco to the guy who wondered how Decker would feel about being kicked out of the center seat to the other engineers working with Scotty—all sound like bored high school students reading off cue cards. Even Mark Lenard—slathered in latex and speaking a made-up language—can’t do anything with his Klingon captain.