Memory Alpha summary
Of particular interest in this debut of the Borg
...is the clash between Guinan and Q!
Let's start with Q. After his debut in the series pilot "Encounter at Farpoint" and follow-up appearance in "Hide and Q," the god-like being to end all franchise god-like beings is on-hand to help shove the series to new and greater heights, like a cue (heh) for everyone to acknowledge that to this point Next Generation had not really lived up to its potential.
Everyone loves Q, though, right? Do I have to do a hard sell for him here? Yet this is perhaps the only other time besides the concept of the trial in the pilot and reprised in the series finale ("All Good Things...") where he gets to be something other than an imp, can be taken seriously, because he forces Picard to acknowledge once and for all that humanity has much to learn. And it's the one and only time he scores on that point, too, beyond a shadow of a doubt.
By introducing the Borg. Yes, the first season teased these most formidable of foes, but it took until "Q Who?" to not only to know what they actually look like, but what they are, what they represent, and that, yeah, they really are like nothing Star Trek had seen before.
I call this a classic although it's to be understood that "Q Who?" doesn't really compare to the series high point, "The Best of Both Worlds," in which the Borg make their biggest-ever impact, in effect giving Next Generation its lasting legacy. For one the look of the Borg isn't quite nailed, although everything else is, including their cube ships that are perhaps more distinctive and menacing than any drone could ever hope to be. The menace of the cube is amply demonstrated all right...
Besides Q and the Borg, there's also Guinan. Throughout the series but especially in her debut season the amiable bartender existed in an impenetrable air of mystery, and only sometimes is there any real attempt to dispel it. Even after two additional appearances in the movies, the portrait remains unfinished, even though she emerges as less than she's suggested to be in moments like the one that helps make "Q Who?" that much more impactful. She is in fact presented as a legitimate threat to Q. Which ends up being, for anyone knows based on all remaining evidence, a wild overstatement, but in this moment it does more than any prior appearance to prove how important Guinan really is. Like Q she ultimately transcends any efforts to limit her despite growing familiarity doing its keen best.
So that's a lot to chew on. Aside from "Measure of a Man," it's hard to conceive of another episode from the first two seasons as significant or worthy of significance as "Q Who?," and that's really all you need to know if you're looking for a simple enough recommendation.
four quarter analysis
franchise * series * essential * character
John De Lancie