Who is the narrator, can she or he read minds, and, more importantly, can we trust her or him?
First-Person Central Narrator
Right off the bat, Vonnegut tells us not to trust Campbell: he's a playwright, which means he lies for a living. More than once, Campbell's quick wit and penchant for verbal flare call his reliability into question.
What's really unique about this novel, though, is that Vonnegut sets us up to regard Campbell as a historical figure in real life, even though he's nice and fictional. What we get, then, is a confessional memoir written by a fictional character that Vonnegut tells us is a little sly.
Even if Campbell is fictional, we still see everything through his eyes. These are his memoirs, and the only perspective we really get is his. Is he as unreliable a narrator as Vonnegut suggests? That's for you to decide.