Well, you know - Stephen King movies have their own special sub-set of rules. :) Namely, if he writes the movie, it'll stink. If someone else does, it'll be good. It's been long enough since I read either Shawshank or Stand By Me that I can't remember if I liked them more than the books or not.
I recently saw a quote from him... wish I could find a link to the exact wording. Anyway, after she was introduced to Stephen King, a lady said something like "Oh, I don't like your books. Why don't you write uplifting things, like that Shawshank Redemption?" He was, predictably, unable to convince her that he wrote it. :)