I wouldn't say he was either good or evil. I think he's unique!! The crimes he commits are, I suppose, evil, but it does it to satisfy his urges to kill, not because he thinks it's good to do so. It's Harry's code that helped him concentrate on focusing his urges on killing the right people, so he doesn't end up going down the same road as Brian, his brother...
I won't kill my sister...I won't kill my sister...I won't kill my sister...