I think Kylo Ren does make an interesting character. Taking a step back to look at it all, He is a conflicted character. He feels the good inhimself, but wants to be Vader. It's why he loses to Rey. He's not fully commited, trying to convince himself he's as badass as Vader, but isn't. He can't handle adversity. When an enemy he expects to be a push over holds their ground, he's afraid. Rey has that moment where she connects to the force, and it's from that that she pushes back and he loses his confidence. Before that point, he was using the pain of his wound to feed into his anger and force use. When his confidence shakes, he loses that and gets his ass kicked.
When he has the helmet on, he's pushing the whole Vader vibe. But when Vader would have killed a nearby Imperial for failure, he just throws a tantrum and damages the room he happens to be in. Very much the adolescent style. Whenever you have those scenes where his helmet is off, it's deliberately showing him as that more humanised, young, not as confident as he tries to appear.
Edit: And for the other Star Wars related news..
Something David Prowse mentioned: