I like Stephen King's novels like anybody else. He really is a master at writing in a really interesting and engaging manner. However, there's one aspect of many of his books that I don't like that much.
Please don't misunderstand. I don't have any problem in supernatural elements being used in fiction, as long as it's interesting and support the fictitious reality of the story. In fact, quite many of King's books containing supernatural elements are just fine, when it's precisely the supernatural element that's the very core of the story. (Classic examples of this include Christine, Firestarter and Pet Sematary.)
However, in quite many other of his books the supernatural elements seem completely out of place, and artificially tacked on. They feel like not belonging to the otherwise interesting story, and they actually detract from it.
King is a master of writing suspense. Many of his novels start in a very suspenseful and mysterious manner, yet remaining in the realm of natural events. They often involve strange behavior by people, or even outright crazy people (who often appear normal at first, but then reveal their true personality.)
But then something supernatural is revealed behind the scenes. (Many times this person or persons were either driven crazy by the supernatural phenomenon, or are themselves actually not normal humans.) This turn of events more often than not feels completely unnecessary, and detracts from what otherwise promised to be an interesting thriller.
To give a classical example of a novel where the supernatural elements are completely unnecessary, take The Shining. This novel could have perfectly well been written without any supernatural elements, as a pure psychological thriller, and it would have worked exactly as well, if not even better. (Of course delusions experienced by Jack Torrance could be described, as long as they are kept just as that: delusions that did not really happen.) The supernatural elements feel artificial, redundant and tacked on. Completely unnecessary.