This episode is just fantastic. Almost everything is great in this episode. The characters are enjoyable to watch as they interact and the chemistry between Charlie and Kirk and Charlie and Rand is just terrific.
The scene where Kirk first disovers Charlie's powers is the best part in the episode. It's so creepy to see Charlie after he makes the guy in the gym disapper where they darken everything but his eyes.
I loved the part in the rec room where Charlie is showing Rand card tricks and he flips the cards over and she is on all the cards. That is another great part.
This episode was written very well. D.C. Fontana and Gene Roddenberry both worked on the story and script so there can't be anything better.
The only part in this episode which I do not like at all is the part where Spock is playing the Vulcan harp and Uhura starts singing. That got annoying pretty fast.