I'm starting to detect a common theme in Vonnegut's work; the absurdity of reality and the futility in trying to make sense of it. And realising this, how can we do anything else but laugh?
This book is a story of one man's conversion to Bokononism which is basically coming to terms with the above and living your life accordingly. It is also an account of an apocalypse in which the invention of a new molecular arrangement of H2O (known as Ice-9) leads to the near obliteration of life on earth.
Some parts of this book made me laugh out loud in public which can only be a good thing. His humour is wry, making light of tragedy but not in a way that belittles it. It's all in the way it's delivered, which I think makes his writing unique.
Don't look too deeply at the science in this book, which surely doesn't bare too close scrutiny, but that's not really the point. Vonnegut is concerned primarily with humanity, using tools from the SF toolbox as needed to make his point.
I'm not a religious person but, after reading this, I can feel the pull of Bokononism.