The Lord of the Rings books were turned into a trilogy. The Hobbit book was turned into a trilogy. The 50 Shades series of books were turned into a trilogy. The Girl With The Dragon Tattoo books were turned into a trilogy. The Godfather books were turned into a trilogy. I think the list goes on and on, so it really does depend on what movies you are talking about. I think Brennan is right, though, the books are much better than the movies in most, if not all, cases. I suppose the only exception would be is if you love a movie trilogy that fans of the book really hate for not being faithful to the story as then the books would feel too "different" to you. That's why it try to always read the books before watching the movies or television shows, except in cases like Game of Thrones where it doesn't look like the books will ever get finished.