I just received my copy of the book through Bol.Com so now I can tell you more about the book - it's basically the script. The book starts with the main credits (writer/director, cast, producer, etc) and then you get the full, entire script.
It's a must have for the fans. I already had parts of the script from when I was in Bruges, but this is the whole deal. If you loved the film, you will love this book. I was reading it on the train and laughing out loud, you should have seen the faces of the people around me. Priceless!