Too much depends on the type of book. Books that have a great deal of backstory or action taking place inside the character's heads typically fare poorly on the big screen (Dune, for example). Books in which the story is largely driven by the environment can fare much better on the big screen than in print (Das Boot). Sometimes both the book and the film are giants of their genre (Princess Bride, Gone With the Wind). Sometimes, but rarely, the movie can be a modified version of the book which stands alone independent of the book (The Postman, The Forbin Project). Lastly, a movie is almost always better than its novelization.

However, both epic tales and short stories can almost certainly be expected to be mangled in the translation. Movies must fit certain formats to be commercially viable, and existing stories must be changed to fit that format.