Good grief, what a goofy grin on Lockwood's face in his title close-up. Who thought that was a good idea?
Nichols looked really nice in that, and she had a good part, too. I don't think she ever got to do anything so deep or emotional in TOS.
And I wonder if Marshall's role as a confrontational hothead here had anything to do with his getting cast in a similar role in "The Galileo Seven."