I've got to ask why the heck is this a classic? I get it shows what we may revert to in a emergency situation but there are many books that do that (and do it better). This book didn't have enough back story and too many characters were randomly named/mentioned but we never get to see how their stories play out.
Also I had also gotten this impression form people describing this book that they all worshiped the pig head, not just one crazy boy who is killed shortly after. It felt pointless and well... stupid.