Amazing books often come with highly anticipated movies that rarely measure up. This disappointment isn't always caused by a poorly written screenplay or bad production; it is just impossible to recreate the individual and unique experience a good book gives each of its readers. As readers, we create the scenes as we read, and it's unlikely that the movie director will have the exact same vision in his/her mind. Also, reading a book gives the readers more time to connect, invest in, and get to know the characters. By the time we actually see our favorite character on screen our expectations are too high for any actor to measure up to.
An example of this is Gone With the Wind. Gone With the Wind is considered one of the best movies of all time. Adjusting to inflation, it is the highest grossing movie of all time, and it is also the first movie to win more than 5 Academy Awards- it won 10! That being said, having read the book before watching the movie, I was a little disappointed. The characters (especially Scarlet, the protagonist) were not nearly as well developed and the movie left out key plot details. This is clearly not an example of the movie simply being bad and the book being good- it shows that even the best of movies cannot create the same experience that reading a book can. Unless you are directing the movie and can create the scenes based on the images in your head, there is bound to be some discontinuity between your interpretation and the movie's, which will end with you leaving the theater unsatisfied.