Regardless of whether a movie is based on a book, books are better for providing the type of entertainment which allows you to escape reality and immerse yourself into a different world as often as you like. You can read a few pages every night but can't really watch ten minutes of a movie every night. Movies on the other hand are a great way to allow your mind
to be a bit lazier and rely on visuals and scripts to entertain you for a couple of hours. With movies things are laid out for you which often doesn't require you to think as much as a book does.
When a movie is based on a book, the book is almost always better as movies. Movies cannot always capture the depth and length of detail that the book gives. Its also natural to compare the movie to the book and it is rare that casting and storyline variations are completely true to the book. Even when you are impressed at how the director has managed to capture the setting just as you had imagined it, included and excluded details that you agree with and the cast to look and act just as you had imagined, it is still hard to say that you like the movie better than the book.
Books also rely on your imagination; you picture settings, people and events in your mind, where as movies tell you exactly what a character looks like, how they talk, what the setting looks like and so on. It leaves very little room for imagination which takes away the extra importance that a book provides.
On a practical level books are also something which can be enjoyed in different places whether you are on a plane, train on your journey to work, at night in bed or even at the doctor. You are more restricted when watching a movie. Although technology does allow you to watch a movie on an airplane or in the car, it is not quite the same as watching it on the big screen or in the comfort of your own house.