John Doom said:

When I say he’s “emo”, I’m joking, of course 😄
I agree he’s been fleshed out. But what’s his purpose in the movie? If he’s a villain, does he work as a villain?
Sure, Luke was a bit cocky in ANH, but his attitude didn’t affect his actions, and so his character: he’s a brave one, he does save the princess, he “does care”, we’re with him when he blows up the Death Star, he’s the hero.
Ren, on the other hand, as a villain, takes off his mask too early, and we get to know he’s just a boy. He’s constantly mocked by our heroes, he’s afraid, can’t take control of the situation and, finally, gets defeated. Is he a true villain, is he actually a threat to the heroes? 😄 If you ask me, no, and this affected the whole movie, especially its second part.