This is a great example of how to tie character development into the plot of your episode. The use of a bug to unearth the crew's inhibitions and self-doubt makes for a great episode and good way for the audience to find out more about these characters. Spock's struggle with emotion, Kirk's conflict between finding romantic love and maintaining Captain-like control, Sulu's... fencing hobby?
All of this further's the development of these characters and makes the audience identify with their plights. Mix this with a little bit of peril and you have yourself a solid episode.
All of this further's the development of these characters and makes the audience identify with their plights. Mix this with a little bit of peril and you have yourself a solid episode.