This episode is far from bottom-of-the-barrel, but does rather have 'average' written all over it. It presents a number of elements that are seen in various other episodes, and often done better and more memorably than here.
By far the most interesting element of the episode to me is the 'mathematical' war that is being raged; where the casualties are worked out by a computer, and then the people in question are disposed with in disintegration chambers. I found this a very intriguing idea, although I did feel that it was never quite explained to its potential.
There are also parallels with the 'faceless casualties' of war, and probably had some nods to the Vietnam War, which was being fought at the time this episode was made.
The episode also features what I consider to be one of the funniest Original 'Star Trek' moments, as Mr. Spock distracts a guard by calmly and straight facedly (what else) saying "Sir, there's a multi-legged creature crawling on your shoulder", before giving him the Vulcan neck pinch.
This is also a good episode for Mr. Scott, as he holds his own as he commands the bridge as the Enterprise is endangered, and stands up to the Ambassador who is ordering him to lower the shields.
All-in-all, not bad, but a distinctively average episode.