Misery is unusual of King novels. Why? Because it isn't supernatural in the least( not counting the little reference to Jack Torrance of The Shining). The book is completely explainable, except possibly the explaination for why the mind sometimes snaps. Psychiatrists study on this particular subject constantly, but for all that, they still don't really know why or when it will happen.
But don't let that deter you. Its every bit as frightening as his other works. In fact more so, we know that there are madmen( or madwomen in this case) out there. Being a writer myself, I feel strongly for Paul Sheldon, being forced to write a story.
Overall I recommend this film, for any horror fan. Note: The movies good also.