I really like Billy Pilgrim as the protagonist. He was kind of simple-minded which kind of made the brutality of his situation even more intense. He describe things with a kind of innocence, but like a knowing innocence. I don't think that really makes sense (but just go with it. No one will notice).
Vonnegut created all these colourful characters that we mostly meet in passing and whom Pilgrim narrates his insight as to how that particular character dies, which is always fun. There were also a lot of heartfelt moments which just made you stop and think. Good stuff.
My favourite quote, which I think kind of captures the heart/theme/mood/essence of the book is the following;
"And then it developed that Campbell was not going to go unanswered after all. Poor old Derby, the doomed high school teacher, lumbered to his feet for what was probably the finest moment in his life. There are almost no characters in this story, and almost no dramatic confrontations, because most of the people in it are so sick and so much the listless plaything of enormous forces. One of the main effects of war, after all, is that people are discouraged from being characters. But old Derby was a character now." (Vonnegut, 119)
So it goes...