Instruct: Classify an Amazon review as either positive or negative.
Query: One of the best of the series

Watching David McCallums acting in this episode has made me a life long fan of his work!The effects are outdated with a poorly constructed monkey suit(literally),and an evolution control lever marked "forward" and "backward" which seemed a little silly to me. But once you forget about that and focus on the story, you'll be suprised at how great this episode has held up 35 years after it's making!