This is indeed a tough book to review. It's about time travel and aliens, and also war and life and death. It's cyclical, even repetitive, and certainly not linear. We know what happens in the last scene before Billy's story even begins. That's intentional, Tralfamadorian, and it's an effect that I can easily see would be annoying to some. But I thought that it was very effective.
Slaughterhouse-Five is described as an anti-war novel. And it is, in a way, but not in the usual way. It's an expression of resigned dismay that war happens, that it's ugly, and that it will kill many, many people. Billy has accepted the Tralfamadorian perspective that things happen, and you can't stop or change events. But that doesn't mean that simply observing events pass you by is a moral alternative.
I listened to an audiobook read by Ethan Hawke. I thought he did a fine job narrating it, and I enjoyed the experience of listening to it.
ETA: I originally gave this book four stars when I reviewed it in April 2012. A year later, I've bumped it up to five. Without my realizing it at the time, Slaughterhouse-Five carved out a place in my mind and my heart. A year later, it's still living with me in a way very few books do after even a few days, much less a year.