Because I was curious and loved the movie, I just read The Invention of Hugo Cabret, by Brian Selznick. What surprises me most between the movie and book is that Martin Scorsese, at least with his last two films, is slavishly faithful to his source material. (Or, the people who write those scripts are slavishly faithful.) Yes, the flair that Scorsese brings to Shutter Island and Hugo isn't found in many books, but Invention of Hugo Cabret, partly because it's almost evenly divided between illustrations and text and partly because it's about film preservation in some way, seems like it was tailor-made for the director.
All of that basically means that I enjoyed the book just about as much as I enjoyed the movie. Had this been around when I was 10 or so, it'd be my favorite book. As it is, I want to own this book so my son or daughter, at that age, can fall head over heels for it.