Ren isn’t interesting
This is a complaint I haven’t heard very often. May I ask why you feel this way?
Sorry for the late answer, just saw this. I don’t find him interesting because he’s just a Vader copy. Deep voice, all black outfit/uniform/whatever, identity hidden behind an ominous helmet, red light saber. Plus, in the spirit of Lucas, he’s a family member. More universe shrinking.
The in-story explanation helps a bit, but he’s still one-dimensional. I should point out that I’ve never found Vader to be very interesting. Not in his original 77 form, not in his rewritten-as-father form a few years later. For me, having Ren as another family member didn’t add to interest.
That’s also why I’m really hoping our new lead is Rey Random, not Rey Solo, Rey, Skywalker, or Rey Kenobi. that said; Rogue One has helped tremendously with my not caring near as much about Rey’s lineage as last year. I have the Star Wars sequel I’ve always wanted. If VIII isn’t what I hope, no huge loss.