I would have to agree with Gore Vidal on that point.  The last time I saw Vonnegut was on a Daily Show appearance, and as with his writing, while I could find grounds to disagree as often as agree with him, I was never bored. 

What I loved about Vonnegut's work was the clarity of his opinions, the sharpness of his wit, the incisiveness of his thought, and the fact that he never shrank from being a gadfly to American culture.  His appearance on the Daily Show closed with mention of his list of "liberal crap I never want to hear again." And his story, "Harrison Bergeron" illustrates the poverty of an equality that denies the value of human difference.  His work was aimed at getting people to think about the consequences of their actions - on themselves, on the world, on each other.   

All of Vonnegut's wit would have been hollow without his humanism.  That, I think, is what most profoundly affected me.  Or, perhaps infected me: I went on a serious binge of his work when I was about 14, a highly suggestible age.  Thoughts like: "A purpose of human life, no matter who is controlling it, is to love whoever is around to be loved" and "We are healthy only to the extent that our ideas are humane" and "If you can do no good, at least do no harm."  Simple phrases, but deeply challenging once you start thinking about how to consistently apply them.

I liked that Vonnegut wasn't afraid of contradicting himself, either.  For all his dedication to humanism, he didn't shy away from talking about God (although he was highly skeptical of this possible God's motivations), as even a quick skim of quotes from his work shows.  But he also said: