Definitely open to interpretation. I read him in the Fall cinematic as being a bit bitter about the whole thing ("I see only darkness before me"), but he does also seem somewhat relieved.

But yeah, it was the whole "tore out his own heart" quest that tries to cement him as wholly evil. It goes with the premise of maybe he got rid of the heart because it contains his conscience or whatever, but finally ends up with "No, he tore it out because getting stabbed in the heart just sucks, and thus removing it means they can't stab it."