This episode followed a well-worn groove when it came to setting up ST storylines. It all seems so familar, not because the basic idea has been used before, but because we've seen the plot devices so many times.
Introduce a female crewmember who will trigger the storyline then be disposed of at the end. In this case it's Dr Anne Mulhall (played by Diane Muldaur), but it's been done before - Marla McGivers (Madlyn Rhue) in "The Space Seed" and Elinor Donahue (Commissioner Nancy Hedford) in "Metamorphosis". Add to the mix one or more super powerful aliens - Apollo (Michael Forest) in "Who Mourns for Adonais?", Korob (Theodore Marcuse) in "Catspaw" and any number of others.
Enterprise crew members taken over by a sinister outside influence - "This Side of Paradise" and "Wolf in the Fold".
It all results is a boring and over-familar episode. You could skip this one and miss nothing.