Soon after I saw TFA, I overheard a teenager reviewing the movie for a friend. He was of the opinion that Kylo Ren was the "worst Sith lord ever", criticized the fact that he was just a kid, and also took issue with the fact that his "unmasking" came so early in his trilogy. Meanwhile, on the internet, the "Emo Kylo Ren" twitter feed has become a sensation.
Now, I find the guy rather fascinating, for one big meta-reason: he does indeed have a whole lot of elements that could easily work against him ("just an emo kid" being high on the list)...and yet, taken together and in context, he works surprisingly well as a villain. Settle in while I list each possible detriment and why it's actually okay.
Disclaimer: I've only been exposed to the material in TFA and its novelization. That should be enough to go on for now, since this is how he's made his all-important first impression.
The Original Trilogy spent most of two movies leading up to the big reveal that Darth Vader is Luke's father. It took most of three before we saw his face. So we expect that kind of drama from Star Wars. But by settling the mystery of Kylo Ren's parentage and appearance early, in Episode 7, the new trilogy not only references those tropes, but also asserts that any future big surprises of Episodes 8 and 9 will be...something else. This time around, it's not enough just to assert that characters A and B are related. Acknowledging that bond wasn't sufficient to solve the conflict, as Han Solo learned the hard way. Whatever Kylo Ren gets involved with next, it'll be more complicated than that. This keeps him interesting, and helps prevent him from being "just another Darth Vader"...despite his best efforts. Let's talk about that.
If Kylo's “Vader 2.0” stylings were decreed only by the filmmakers and given no explanation whatsoever, that would indeed be unoriginal. What saves him is that the emulation is deliberate on Kylo's part and stems from his own fears. It's very clear that he's not wearing the mask just because some costume designer liked it, or even because it really, truly suits him: he's hiding, and the more perceptive heroes call him out on it.
There's a solid helping of self-commentary in his costume too. Darth Vader generally gets top billing in Star Wars merchandise, including items meant for children. Kylo Ren is an in-universe Darth Vader fanboy who's jumped completely off the Dark end. I feel like the filmmakers are kind of jabbing us in the ribs and reminding us, "You do realize that guy is an absolutely terrible role model, right?"
Kylo Ren is an insecure young man who has become a tool for dark forces. He is aimed and driven by someone who uses him for their own ends, and by his admiration for someone he never actually met. He murders his own father not because of any really specific slight that he can name, but just because it's the Dark thing to do: a philosophy that seems to give him purpose.
He's in a similar category with real youths who latch onto some harmful ideology, and convince themselves that the only way to respond without a trace of weakness is to find a gun or explosive-filled jacket and hurt as many people as they can. This is the kind of enemy we recognize, extrapolated into superhero levels. He's a reminder that such people are actually very, very dangerous if they're allowed to get their hands on too much destructive power.
But that's not the only villain archetype Kylo fills. The last time he tries to manipulate Rey includes a particular lie: he tries to turn her to his side by telling her she needs a teacher. No, Mr. Ren, she does not--well, not you, at any rate. Rey has no formal training with that lightsaber, she is running completely on vapors and righteous anger, and she is still kicking your ass. Well done, sir, you've walked up to a perfectly self-reliant woman and tried to convince her to follow your plan by telling her she's not “good enough” without your help. That's another enemy we recognize, all too well, and we love Rey because she doesn't believe him for even a second.
(For supplemental reading, might I direct you to Captain Awkward, where the term “Darth Vader boyfriend” (or girlfriend, or whatever) has a very specific meaning. Be forewarned that the site deals with adult topics.)
The two are perfect foils for each other: both young people trying to make sense of the power fate has given them, each clearly expected by their elders to perform great deeds, but taking guidance from opposite sides.
There's a nice bit of characterization that is present in the novel: it states that just after Kylo Ren kills Han Solo, he has a feeling that the act should have made him stronger, but didn't. It's not quite regret, but it's close, and I wonder if there will be any hint of it in future installments. Like Rey, I wonder what will happen next--on both sides. Any villain who leaves me with that curiosity has done their job well. So congratulations, Kylo, for working out so well despite so many chances to do otherwise.