Yeah - Brook certainly has potential to be a unique, multi-layered, and interesting Strawhat. He's the oldest guy on the crew, and however much he tries to hide it behind goofiness, he has to have seen and learned SOME things that would make the other Strawhats' skin crawl.

I envision that at one point or another in the future, he'll be dispensing some offbeat (and maybe depressing) sage advice to Zoro or Sanji, much as they might to Chopper.