If you’re read the book, skip the movie. The Da Vinci Code is at its heart a mystery suspense thriller. If you already know how it all turns out, then there isn’t any mystery and hardly any suspense. The book had a wonderful pace to it. The movie seemed to jump from situation to situation without much of the “solving the puzzle” aspect of the book and I kept commenting to myself, “we’re here already?”
On the other hand, someone who hasn’t read the book and wanted the Cliff Notes version, might save a few bucks by seeing a matinee instead of buying the book.
Folks say “of course it’s a work of fiction”, but that’s not quite right. The book claims to be a fictional story set in a factual landscape. The factual landscape isn’t quite factual. Some of the facts are simply wrong, some of the opinions are “fringe” among scholars and sometimes one is misdirected into accepting conclusions from facts when there are alternatives.
So either the book or the movie (but not both) is a suspenseful mystery. But don’t try to get a history of Christianity from it.