First off, the book is much better than the movie version.
Second, the burning of books scene in the movie like that in Fahrenheit 451 and the Day after Tomorrow is simply sickening to bibliophiles like me. This scene is not in the book.
Third, Mo and Dustfinger are not that antagonistic to each other in the book, the swapping of the Inkheart book with another and other changes. I hate it when changes like these are made in movie versions as they tend to change the motivations expressed in the book. Directors/screenplay writers think nothing of these, but remember the changing geography (example: Hagrid's hut) in the Harry Potter movies?
Fourth, Elinor, whose book collection is described in the book's chapter A House Full of Books, doesn't look too distraught over the destruction and burning of her precious books in the movie. Is it a case of too-subtle acting on Helen Mirren's part? I was cringing in my seat watching pages fly all around in her small library (in the book, even the guest rooms are filled with stacks of books) while Mirren socks one of Capricorn's men in the face onscreen. Why, I even shed tears everytime I had to burn the remains of my books attacked by termites at home.
Fifth, admirably the movie follows through the book's intention of promoting reading and respect for the word.