Just my opinion, but I think it looks really good as a black and white piece. I would consider keeping it that way and maybe redoing it on nicer paper. I guess it all depends on what you want to do with your work and your portfolio.
Don't get me wrong, I also think it works as a colored piece. I would amp up the shadows on the colored version to create the moody feel you're aiming for.
Can't wait to see where you go with this. It seems like you have really strong drawing skills!