This is another book about war. That seems to be a good topic if you want to have a "greatest book". I think if you can write a book and include war, racism, sexual openness, and question religion then you will be golden.
What I really liked about this book is that it helped me to see just how young the soldiers in a war really are; especially back when soldiers were drafted right out of high school. To think these young men had their entire life ahead of them and off they went to die. Just awful.
I thought Vonnegut's system of including time travel, and even space travel, were very interesting and I was surprised how fluid such a mixed up system turned out to be.
Oh, and the Slaughterhouse was actually an old slaughterhouse that they used during the war to keep prisoners in. I was afraid it was going to be some gruesome place where they killed the soldiers. I was glad it wasn't.