Nimoy didn't want to do this episode and with good reason. The plot holes are enough to drive a Buick through. McCoy seems to know just how long Spock's body will live without his brain, despite knowing nothing about the procedure and next to nothing about Vulcan physiology.
Don't even get me started on the remote-controlled Spock with the ten-button remote! (I think the lower right button is the "wrest control from alien woman and push the red button to free your crew" control.)
Watch it for completeness' sake, but don't judge the rest of the series for it!