Captain Kirk has to welcome Charlie onboard. Charlie is an odd character, which we don't know about. When he meets a girl for the first time, he simply slaps her ass - hello 1960's. This is a time before the #MeToo movement. Or even hashtags for that matter.
It was interesting to see the crew chill out, with Spock playing some music and Uhura's singing. This could have been easily ridiculous, but the director was actually able to pull this one off. But unfortunately, there is actually a scene at the gym that is ridiculous, with Kirk topless wearing tight red pants, trying to teach Charlie how to fall and fight.
I was impressed by the original score. This is a time before cheap synthesizer TV music, thank God.
WHO IS HE/IT?
Overall, the episode is definitely enjoyable. The great thing is that we keep wondering about Charlie until the end of the episode. In a way, this episode is very similar to The Man Trap, the previous episode, where we would be left wondering about Nancy until the end of the episode (she was actually a monster).
The end is really satisfying and most of the episode is actually good, simply because of Robert Walker Jr., the great actor portraying Charlie.