If I had to complain about anything in this classic episode, it's McCoy's attitude about the men below. "What if death was caused by transporter malfunction? Then you'd die. They'd die anyway."
"They'd die anyway" always felt too cold for McCoy. What the hell did Sulu do to him? The guy's a doctor. Even if the line stayed, the delivery could have been a little different.
Other than that, a solid 9 or 10. Easily in my top 5 Trek's ever. And god what a great score!