Abrams made a conscious decision to have Ren look younger (Driver usually sports a beard) and I think Hux was supposed to be an old guy at first. Hux is interesting and scary too. When you watch the Death Star briefing scene, you get the idea that a lot of those officers are probably in it for the money or the power. But Hux is like a Hitler youth. He’s not in it for himself, he’s in it for the cause. He actually believes the First Order is right and just - that’s scary.
I was more than OK with Adam Driver in this film for the most part. Until he was unmasked, I liked his character much more than I thought I was going to. I would say that up until he was unmasked, his performance was one of the strongest parts of the film. That said, when he took off the mask he was not intimidating or convincing. Either keep it on or cast someone else in that kind of role.
As for Hux (Domnhall Gleeson), he gave one of the two worst performances in the entire film. His acting, if you can call it that, was cartoonish. The only thing missing was him twirling his evil villain mustache, but that’s simply because he didn’t look old enough to even grow one. Some of the casting decisions in this film were incredulous. As much as youth was needed in some parts (Daisy in particular was fantastic) other parts called for age and experience. How does someone who looks 25 get to be the senior most military commander in something like the First Order? Except for Harrison Ford, whose salary basically forced the entire script to be unnecessarily written around him, who else gave an experienced and nuanced performance? Where were the Alec Guinesses, Peter Cushings, James Earl Jones’s, and Kenneth Colleys in this film?