There is a definite reason why the book is almost always better. Books, especially novels, run into the hundreds, or if you're Stephen King, into the thousands of pages. Screenplays and shooting scripts have only about a hundred to a hundred and fifty pages, most of them being taken up by the white space between paragraphs.
The very very difficult job of ripping the bare bones of the story out of all of those pages gets delegated to the screenwriter in the transition from book to script. Something always must be left out, and quite often, it's most of what people liked about the book in the first place. All of that gorgeous descriptive language talking about The swirling of the snow as it falls from the looming grey sky on the cold November day gets compressed down into "ext. snowstorm" on the page.