Vonnegut wrote "Slaughterhouse 5" in 1969. It is a mixed genre of sci-fi and war. Vonnegut wrote it to show people the 'American dream' as being false and not having real value, only materialistic value. The question is asking whether Slaughterhouse 5 is depressing or optimistic and humorous, or maybe it is just sad but the humorous manner makes it feel optimistic.
Just by looking at the title 'Slaughterhouse 5', the idea of a place where things got killed is gruesome and depressing, but this title is also a pun because it is meant to have another meaning. If you take away the 'S' of 'Slaughterhouse 5' it is 'laughterhouse 5' which gives the book an entertaining, optimistic look.
Vonnegut uses this war story book as an anti war-book. He uses the way in which Billy jumps from one stage of his life to another, uncontrollably, 'Billy is spastic in time' to represent how chaotic war was.
He shows how people think of war as being great, manly and herotic:
' "You'll pretend you were men instead of babies, and you'll be played in the movies by Frank Sinatra and John Wayne or some of those other glamorous, war-loving, dirty old men. And war will look just wonderful, so we'll have a lot more of them. And they'll be fought by babies like the babies upstairs"[...] And she thought wars were partly encouraged by books and movies. '
This quotation criticises the way in which wars are glorified and encouraged by films. This is saying that people think that people with guns and war machinery are really manly like in films but underneath this front they are really like weak little babies! It is also saying that men shouldn't act like babies and fight...