It's a great book, Vonnegut is one of a few authors who GETS IT. He understands what is really going on and still manages to retain enjoyment of life despite the pointlessness and rudeness of it.
A good article by him, explaining his points more explicitly:
http://www.inthesetimes.com/article/cold_turkey/
Waiting for Godot - I do not understand how that relates to Slaughterhouse Five. It does not.