Well, at least for the first series I suppose!
Actually I like this (as I like most) episode because of the base message and it's inherent pessimism. I mean, only Star Trek, at least in those days - would come out and say something like "good and evil use the same tactics, get the same results" - sort of taboo even today in the light of things like beheadings and abu ghraib in Iraq just a few years ago.
Maybe I'm taking it too deep but the series fully intended it to be read so in those days. They were trying to find a way out of the Viet Nam war and.... this was a micro chasm of that angst. I wasn't alive then, but it was just short of a national civil war at times: this country was mentally ill. Colin Powell was recently asked if the times we're in right now (2012) are the worst he's seen and he said "No way! The cultural revolutuion of the 1960s and 70's was much MUCH worse!"
Anyway, the acting is pretty darn good considering that this episode is clearly one of the most implausible upon implausible upon implausible scripts and storylines in the whole ST universe really. And you have to enjoy Spock and Kirk getting their rocks off and their hopes fulfilled meeting their life-long all time idols!
And...the message is true; war is bad no matter what side you think you're on.