He's like Bruce Willis, in that he's a cool, badass action star but he's also proven to be a very solid actor (not on Willis's level though) when taking more daring parts. He AWESOME in I Heart Huckabees. He had some intense moments in Three Kings when he gets captured. And, even though he was overshadowed by Christian Bale, he was still very solid in The Fighter.
So I may not be quite as enthusiastic about him as the original poster, but I am definitely a big fan of his.