A few days ago I rewatched The Perks of Being a Wallflower and one of the first things I noticed about the film was who the director was. And the director was in fact Stephen Chbosky. And if you didn't know he also happens to be the writer of the book. I liked that idea, because that means that key features in the film were less likely to be changed in comparison to the book. I loved the film and would defiantly give it a 9/10!!
I have never actually read the book but I've heard its brilliant. I do have it at home cause I asked for it for my birthday but not yet read it. Its on my near future list of books to read. :)