I like him completely villainous. He is just that character that needs to be that ONE villain who is always going to be that way. Every good superhero needs that ONE person (or two) that they know eventually it will come down to a situation of, "them or me".
I'm quite interested in Clayface trying to find redemption--even the Riddler. But Joker has always been THAT iconic key villain who should be Evil Incarnate.