It's empirically true that they didn't communicate Kylo's wounded-ness well enough, since tons of people weren't satisfied with it.
And even if we can construct an explanation about how he wasn't in top form, it's a lame script decision to have your previously-menacing bad guy just become a total jobber. Nobody wants to see the villain be ineffectual. So maybe we resolve that by realizing he isn't the villain, but then that means his awesome introduction at the beginning sold us a bill of goods. AND while the "seduced by the light" line is cool and evocative, we don't really spend enough time with him to really get what that means.
The fight just isn't satisfying. However we frame it to make it consistent, we're left with in situation where Kyle is poorly rendered. That fight is a job because it exists to give Rey a victorious awakening but it does my boy Kyle dirty. Kyle's arc gestures at intriguing ideas but doesn't actually articulate any of them.
(This basic criticism also holds for Finn and Rey though, so in the end we can say that the movie kind of dropped the ball. It's sort of lame to say "this movie is just a lot of stage-setting", since of course it's part 1 of a trilogy, but the result is that the movie is frustrating on its own in a way that A New Hope, say, wasn't. This movie *requires* a sequel. Hell, it requires a prequel, too, given how poorly-drawn the Republic / Resitance / New Order are.)