The Davinci Code is a dreadful book. The plot was copied almost verbatum from academic texts and the structure of the book was very annoying.
But I finished reading it. I had a long flight delay and there was nothing much else to do
I've read Umberto Eco's Foucault's Pendulum and it's a great and challenging read.
I discovered Eco when I read The Name Of The Rose. Great book too, and the film wasn't too bad.
Stephen King I read as a kid and thought The Shining was ok, but he has really gone downhill since he came off the coke.