I think Christopher is a darkhorse. He had some redeeming moments - mainly some of the scenes with Adriana where he seemed to genuinely care for her and some of the scenes where he fought his substance abuse addiction. Of course, he also beat Adriana on a semi-regular basis and signed off on her murder.
I think what made me dislike Chris so much was the way he treated laypersons. Particularly, he had that writer friend in the program that he just treated like pure dog#### (yes, the guy did delay on some payments but still). He kills him for no reason in one of the last few episodes - after the guy let him into his home to try to help Chris address his one of many backslides. Tony and some of the other guys seemed to really adhere to the unwritten rule that unless a civilian wrongs you that you leave them alone and/or treat them respectfully. Chris tried to sometimes - especially with the movie plotline - but couldn't ever really do it. And, instead, he treated them poorly (probably out of jealousy).