You know how it is. Somebody has just posted on Facebook that they have watched some film or another and you are suddenly filled with an overwhelming urge to tell the world how much better you are than a person who simply sits on their arse watching a screen for ninety minutes. But how do you do so without appearing a complete arse yourself? I will tell you.
Do not say, "I much preferred the book to the film." This is blatant passive boasting and really gets on everybody's tits. Instead, say something along the lines of, "I enjoyed the film. I thought the cinematography was particularly good. I also loved the book especially…"
Making the assertion of your intellectual superiority over mere moviegoers an afterthought considerably lessens the obviousness of the boast and doesn't slap down your friend who made the mistake of admitting to liking a film adaptation in the first place. You come away from the encounter as a person who is definitely above the common herd but also a person who is prepared to show an interest in the things that ordinary people like doing. Well done! You are well on your way to becoming an Anglican priest if you are not one already.