We’re not supposed to take Kylo Ren seriously because like Luke he has yet to finish his training. Once he does there’s no telling how stronger he will become. Also seeing as how he has fully given himself to the dark side the worrisome traits he has exhibited are going to be exponentially worse. I see Kylo Ren as an idea that has yet to be fully realized.
He got weaker in the dark side as the film went along though. That’s the problem some people have with this character. It would have been so easy to fix too. He should have just wasted Finn, then play-fought Rey, only allowing her to live because he’s attracted to her, or he wants to train her or something. Then she taps into the force and fights him off for just a moment, then deus-ex-machina, the ground opens up and she escapes. Kylo would still be a threatening obstacle heading into the next film, and his arc wouldn’t have blown up.