I have both this original pitch, the writer's bible for TOS and the writer's bible for Phase 2 on hand, all bought from Lincoln Enterprises back in the 70's.
They can be very intriguing: Uhura "can do an impersonation at the drop of a communicator." (p14, Star Trek Guide, 1967)
They can be very contradictory: it criticizes a scene where "Kirk puts his arms about his lovely Yeoman, comforting and embracing her as they wait for seems certain death." (remarkably similar to a scene in "Balance of Terror") But this scene is criticized on the first 3 pages of the Star Trek guide, 1967.
And something Modern Trek failed to realize: "This time is 'somewhere in the future'...happily eliminating the need to encumber our stories with tiresome scientific explanation." (p. 3, Star Trek Proposal, First Draft. March 1964)
Interesting reading; get a copy of each if you can.