It's not a good ep, but it can be campy fun. My favorite Garth line is when he just gets fed up with Spock's contradictory answers and yells, "REMOVE THIS ANIMAL!"
And oh yes, the lovely Marta, played by Yvonne Craig, who also played the scrumptious and leggy Batgirl! She and Uhura (esp. MU Uhura) were the hottest TOS women of all time!