Specifically related to Harry Potter but it applies equally to any movie based on any book!
DS is watching the Harry Potter Houses thing on Sky and the majority of the questions seem to relate to the movie (what happened next, where is this from etc etc). That sent me on a bit of moan about the movies and DS.. DS to my HORROR said the movies were better than the books 
DS is an avid reader as well so its not even like he has the excuse of not liking reading to hold such a wrong opinion.
We've had a spirited debate about it and agreed to disagree whilst DS reads the books as he can't remember them from first time round and I watch the movies as I gave up after the utter atrocity that was Goblet of Fire 
So .....
AIBU - yes absolutely... movies are better, easier to digest, and bring grest stories to those who otherwise wouldn't access them.
AINBU - DS is a heathen. Books are where its at.