I have to disagree strongly. I think with you it's a case of reading the book and expecting the film to be the same.
I'm usually disappointed when that happens. But I just look at the film completely seperately.
Jack Nicholson is brilliant and totally convincing and Shelley Duvall is also convincing. Stanley Kubrick pushed her to the brink to get those performances out of her, making her do scenes over and over again to get the desired effect. The hotel was completely terrifying and and the music also matched this.
This is one of my favourite films. I don't see how you could say this was the worst film ever. SounRAB more like your biggest disappointment for a film ever.
PS I also love the book alongside all of Stephen Kings books.