I actually think that is true in most instances.
Just take Harry Potter for example. At least for me, there the books were far better than their movie adaptations.
I think it's often because the books have so much more depth; a movie that goes beyond two to three hours is very long, but a book that would take 10+ hours to read... that's not really a problem. And yes, I know that in a movie you can express a lot in a shorter time than it would take to read the same description, but all the same, books just offer more time for the author to really give the full picture and a movie simply does not have time for this.
Another book that was in my opinion much better than its movie was the Hobbit. With the Lord of the Rings it's more of a debate for me, because the books have a magic that the movies couldn't have because of the constraint in time (and those movies were already long!) but the movies were so much more approachable and far more geared towards telling a story, rather than recounting history, which is often what the Lord of the Rings books feel like when you read them, and that is just not for everyone, or even always for me. Sometimes I'm in the mood for the far more approachable story presented by the movies.
For Divergent I also by far preferred the books, although the movies were not bad either. The books were just better - especially the first book! I really liked that.
Thank you Cassie for the signature!