The Romulans:

In comparison to the first season I think season two is slightly weaker. On the whole season two is kind of solid, a lot of solid episodes but where I graded 11 season one episodes an 8/10 or higher, out of 30 episodes including the pilot episode, I graded 8 episodes an 8/10 or higher of season two, out of 26 episodes. I am a fan of Romulan stories, in any Trek show, but this season they dropped by only one time in “The Deadly Years”, but it was by far not as exciting as season one’s “Balance of Terror”. When the Romulans come into play, it gets more interesting but other than that I thought it was a mediocre episode. Plus, I always have a bit of an issue with aging a young cast, certainly back in those days, it doesn’t hold up too well in my opinion. Conclusion is simple, I really would have liked 4 or 5 Romulan episodes, or even more!

The Klingons:

The Klingons return three times this season, in “Friday’s Child”, “A Private Little War” and of course “The Trouble With Tribbles”. Yes, the last one if really fun, a comedic episode, laughed out loud several times. The first time I laughed out loud was right at the beginning of the episode, a small joke, but really funny: Capt. Kirk: How close will we come to the nearest Klingon outpost if we continue on our present course? Chekov: Ah, one parsec, sir. Close enough to smell them. [grins broadly] Spock: That is illogical, Ensign. Odors cannot travel through the vacuum of space. Chekov: I was making a little joke, sir. Spock: Extremely little, Ensign.

The other two episodes where we see the Klingon’s okay at best but in “Friday’s Child” I had the biggest smile on my face when McCoy is “talking” to the baby in the final scene of the episode: "Oochy-woochy coochy-coo, was just hilarious! But otherwise a mediocre episode, this Klingon was not (obviously) in the same league as commander Kor (John Colicos) from the season one episode “Errand of Mercy”. “A Private Little War” to me was one of the weaker episodes, having said that, I only graded one episode lower than a 6/10, “Catspaw”, my least favorite episode of the season. Kirk returns to the planet where he spent time 13 years before. A friend from his previous visit is now leader of his people. While trying to uphold the Federation's prime directive, the Klingons are providing more advanced technology to their enemies. Note - It does pose an interesting and often presented dilemma that the prime directive prohibits to help a people technologically, but for some reason, I didn’t love it. What I did like was that Kirk was so worried about his friend Spock and also Miss. Chapel, holding his hand for a moment when she thinks no one can see it and Spock doesn’t know because Spock seems unconscious, but according to Dr. Benga, he is semi conscious and he (Dr. Benga) did see her holding his hand. So, 3 Klingon stories, perhaps a right number of episodes but I only really loved one, the other two I found to be okay at best.

The best episodes:

The season opens really strong with “Amok Time” of course, where Spock, in the wake of his Pon Far, must return to Vulcan to meet his intended future wife, betrothed from childhood. T’Pring chooses Kirk to be her champion, because she doesn’t want to marry Spock. logically, Kirk is no match for Spock, McCoy has a solution for that. Note - When Spock thinks he kills Kirk, the madness has gone and he no longer has any interest in her anyway. He intends to turn himself in, for killing Kirk, till he sees Kirk alive! For a moment he seems to explode in joy, but he regains himself quickly. Of course, Mr. Spock. Your reaction was quite logical, McCoy says. Spock thanks him, then McCoy says: In a pig's eye! I did think Kirk was waiting too long to approve Spock’s request to go to Vulcan, it is his dear friend and first officer, why does Kirk needs to have an explanation after seeing Spock struggle with it?

On everybody’s list is “Mirror Mirror”, a transporter accident places Captain Kirk's landing party in an alternate universe, where the Enterprise is in the service of a barbarically brutal empire. Note - Perfect episode, nice to see a logical Spock in the parallel universe as well. Takei must have had the time of his life acting like an asshole! Nice scene when our Spock putting the barbaric Kirk in the brig and that Kirk was trying to bribe him, fascinating! Last scene of the episode was also fun where Kirk and McCoy ‘feel’ insulted by a clever Spock.

Next one is “Doomsday Machine”, definitely one of the best this season. The USS Enterprise encounters the wrecked USS Constellation and its distraught commodore who's determined to stop the giant planet-destroying robot ship that killed his crew. Note - After what Decker experienced, I think it would be mandatory to do a medical exam, certainly not become the next commander of the Enterprise. This next quote/scene gave me a lump in the throat, very emotional response from Decker which was very understandable: Matt Decker: They say there's no devil, Jim, but there is, right out of Hell. I saw it! Capt. Kirk: Matt, where's your crew? Matt Decker: On the third planet. Capt. Kirk: There IS no third planet Matt Decker: [anguished] Don't you think I know that? There was, but not anymore! They called me; they BEGGED me for help, four hundred of them! I couldn't... I-I couldn't...[begins sobbing]

“Journey to Babel” is just another great episode, the Enterprise hosts a number of quarrelling diplomats, including Spock's father, but someone on board has a murder in mind. Spock’s father has not talked to his son for 18 yrs for choosing Starfleet instead of the Vulcan Academy. When Sarek gets sick, only Spock can help him with a blood transfusion but when Kirk gets injured, he (Spock) feels that the safety of the ship comes first. Kirk pretends as if he is okay for Spock to go to sickbay. Note - First moment is great when Spock tells Kirk he is not going to his parents on the surface because they are here: Sarek and Amanda. The ending is funny where McCoy finally gets the last word. I already mentioned “Trouble With Tribbles”, so much fun, really enjoyed it, almost as much as I enjoyed DS9’s tribute to Star Trek’s 30^th anniversary back in 1996: The Trouble with Tribble-ations.

I also really liked “The Ultimate Computer”, Kirk and a sub-skeleton crew are ordered to test out an advanced artificially intelligent control system, the M-5 Multitronic system, which could potentially render them all redundant. Note - It amazes me how in the late 60’s they already were ahead of its time, having stories like this, something that is coming awfully close in our present time. Strong episode. I actually also enjoyed “Bread and Circuses” quite a lot, more than I anticipated. The Enterprise crew investigates the disappearance of a ship's crew on a planet that is a modern version of the Roman Empire. Note - I honestly didn’t remember much of it, it was 10 years since my last rewatch, but I thought it was quite entertaining. A few nice moments, one where McCoy and Spock are locked up together and they have that little talk, where McCoy confirms to Spock that he is worried for Jim too. Another comedic moment when Scotty is thinking about the possibility to help the trio without disobeying Kirk’s orders. What I found illogical, pun intended, was that Merik and Claudius believed that Kirk would agree to sent down his crew! Putzes!

Final episode of the season “Assignment: Earth” was also strong, really enjoyed it. While back in time observing Earth in 1968, the Enterprise crew encounters the mysterious Gary Seven who has his own agenda on the planet. Note - one thing I don’t really understand, the Enterprise would return to the 20^th century simply for research? I would think this would only happen when there is no other option but to go back. The NASA footage was impressive though. Apparently, according to a reviewer on IMdB, Gary Seven was intended to get his own show together with Roberta Lincoln (Terri Garr) and this episode was supposed to be the backdoor pilot for this. I think I would have been interested in this Gary Seven TV show.

Final Word:

So, yes, season two is in my opinion weaker than the first season, still, I really enjoyed it. In the past I sometimes found it hard to see through the time it was created, but I no longer have that, Star Trek TOS is as relevant today as it was back then. The same issues are there in real life still: wars, discrimination, corruption and even AI. Besides that TOS gives you something to think about that is still relevant, it is also still very enjoyable. There is only one Kirk, one Spock, one McCoy and so on, these actors portrayed these characters back in the 60’s and later in the movies, all the other actors portraying these characters in these current shows or Kelvin timeline movies, are not in the same league as the original actors, not by a long shot.

Screencaps taken from TrekCore

I've added the word document with the episode ratings with descriptions and comments for the ones who are interested in this. Just be aware, it is a draft document, sometimes also can be confusing because of grammar errors and some sloppiness.