"The Enemy" is incredibly similar to a number of episodes in franchise lore, all of them basically inspired by the movie Enemy Mine. One of ours ended up having to survive on a planet with one of theirs, a "good guy" and "bad guy" working together. It has another subplot that's also been used multiple times, a medical dilemma concerning one character not willing to help as another is dying simply because their species are or have been blood enemies. Also, it's basically "Balance of Terror" from the original series as well.
So there's a lot going on, and most of it ends up with Three Stooges Syndrome, stuck in the doorway because none of the three wants to give way to the others.
But what you may take as a unifying element is that it's a Romulan episode, and Next Generation is generally good for these. This one's just disturbingly generic about it. The franchise itself probably realized that when it kept trying to redo some of its elements in later series. Sometimes it's because a story is good. Sometimes it's because the story could be better.
The hero of the first element is La Forge, and this is mostly relevant because the Romulan he's trapped with ends up noting that his kind would have ended La Forge's life after it was discovered that he was blind. Being blind tends to dominate La Forge's character, when necessary. It's seen as a handicap, except when it isn't. In this same episode his VISOR is an asset, a great piece of technology that allows innovative solutions to problems.
Worf is the subject of the next element. His parents were murdered by Romulans. He refuses to donate blood that would save one in the present. It's Worf being controversial, much as he would be in the Deep Space Nine episode "Change of Heart," making a decision that could adversely affect his career. This time he gets off much easier. Next time he's told he will never advance in rank again. Half of this is Worf being Worf, but you can't help feeling that it's because he's Klingon and the writers think it's easier for an alien to get away with this and not seem like a monster (although in DS9 he's saving his wife Jadzia), regardless of Klingon honor. I don't know. It's an odd episode to reconcile on that score alone.
"The Enemy" also features the debut of Tomalak, a faintly recurring Romulan played by Andreas Katsulas, later to become famous as G'Kar in Babylon 5. Part of me wishes that the episode had downplayed the other elements and played more like an updated "Balance of Terror," a duel between Tomalak and Picard. Would fans have been upset? I doubt it. Well, probably. Star Trek fans are rabid. (Though I personally don't bite.)
All of this means that "The Enemy" is an episode well worth watching, but how much you care to remember it depends on how much you care about these particular characters having these moments that happen again to others.
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Memory Alpha summary.