He is a murderous bastard, but he strikes me as relatively ineffectual and (mostly) harmless as a result.
His sister scares the crap out of me.
Eyes of death. Frightening.
He only remains in power if his generals are well fed, wealthy and possibly also fear him. Also, if his Chinese backers are happy with him. If either of those groups is especially unhappy, Kim Jong-Un will quickly succumb to a case of lead poisoning.