I think he had some really good ideas in him, but wasn't always great at execution, and had some pretty lame ideas too. I think "The Cage" is a solid piece of science fiction and an effective character study of Pike. Yet many of his credited scripts or stories for TOS are loaded with silly parallel-Earth stuff ("Bread and Circuses," "The Omega Glory") or rampant sexism ("Mudd's Women," "Turnabout Intruder").
To be fair, I don't think the word "sexism" was even coined until 1970. Probably in response to something Roddenberry did.
But whatever you do, don't mention The Questor Tapes to Nimoy. I hear he's still bitter about being dropped from the lead role.
The Robert Foxworth role, or the Mike Farrell role?