To be fair it is kind of hard to say he's a wholly good person when he would be perfectly happy just killing every noble. Do they deserve it? A lot of them, yeah. But he literally had to be convinced that Elend was different, and that convincing took Elend literally risking his life. Plus there was the time he had Demoux beat up and nearly kill Bilg through no fault of his own, Bilg had, like, a tiny bit of doubt and Kelsier inflamed it, as I recall. He's not a wholly terrible person, but he is definitely an anti-hero and very probably a sociopath.