I don't like to be that person who says the book was better, but in this case I couldn't enjoy the film because I had read the book. The film felt rushed and it lacked deepness: the story, the characters and the relations between them lacked deepness. Everything happened really fast and what we got to see from the main character's childhood wasn't enough. Since it lacked deepness, some moments seemed like they made no sense.
My boyfriend hadn't read the book, but he went to see the film with me and he also felt like it was rushed and that they just tried to summarize a complex story with complex characters.
It's a very good story though and it will keep you entertained, specially if you know nothing about it. Also the acting isn't bad at all. I give it a 6 based on the film itself, ignoring the existence of the book.
Anyway, I hope you get to enjoy it.
