Books or Films?

Actually, people prefer go to the cinema to watch a film rather than reading the book.
I have always said that we do not know the importance of read books. Read books is not only read the  typical book that your teacher obliges you to read for an exam, read a book is a way to create a new world, to feel new feelings that you do not feel in real life and also to find little details, descriptions that you do not see in the film. I have many examples of this, such as Harry Potter's saga. All of this books are better than the films, and it is because in the book J.K Rowling put many important things, many details, which  do not appear in the films, and all of this details are essential to understand the movie, but obviously you do not know this thing if you do not read the books before. Other thing that I hate is  people that do not read the book because they do not like the film, my question is : When we judge things without know it? There are a lot of books that are much better than films, but also there are  films much better than the books, but one thing is clear, we can only express our view If we watch the movie and read the book.