There are a lot of books which are represented as a films. Of course they have the whole idea, but in some details they are different.
Reading a book and watching a film have a big influence both on health and mind of person. The book makes people to read every detail episodes and use your own imagination, while film demands only to watch the one unite short story. During the reading, you imagine the characters of book according to the characteristics given in the text and make them in your head as you want. But in the film there are finished ideal heroes. Moreover in some cases they do not suit to their descriptions. And it can disappoint you. When you watch a film you become a critic of director, but in the reading you are critic of writer. And it is better to criticize book then film because you know the real information, but in the film you do not know what was written at first. And also the vocabulary of book is very clear without any bad words which are usually in films, and consequently it can improve and increase your vocabulary.
But from the other hand reading a book can take you few days while watching can take you few hours. During watching a film you can lie, eat, sit or do some different things, but when you are reading a book you cannot wash dishes or eat. You and your friends can go to the cinema and watch film together but in reading you are unable to do it, of course.
Taking everything into account we should say that it depends on person what to do. As for me I like to read a book than watch, but sometimes I prefer to read and then to watch. And after all of these to compare and discuss. It gives me a big pleasure!