I give this one a solid 8. We see Uhura and Rand fleshed-out some and we even get to see another side of McCoy and Kirk to varying degrees. I also liked the ship's gymnasium.
The story isn't all that complex but Robert Walker JR does a magnificent job bring dimension and color to Charlie. We also get to here Roddenberry as the ship's cook. To top it all off we find out that the turbo lifts have a quality similar to that of the "Bat poles" given their apparent ability to change Kirk's tunic between scenes.
A confident 8.