Ok, everyone else it seems has said their two cents worth about the book or movie, now it is my turn. I just finished the book and found it to be an enjoyable page-turner. It held my interest, even though, as I often do when reading books like that, I had already checked the last chapter to make sure everyone survived. I will also say that I generally prefer reading bodice-buster romances to classic literature. I have always loved to read but generally did not enjoy literature classes at school--or many of the books we were assigned to read.
But what about what it has to say about the Church? If you haven't read it, basically the premise of the book is that Jesus and Mary Magedelean were married and had a child--a child who has descendents living today in France. The "Holy Grail" is Mary Magedelean and some papers buried with her which basically show that Jesus was a feminist, that he meant for MM to be the head of the Church, not Peter. They say that Constantine, who was a pagan, decided to make Christianity the religion of the empire and basically merged pagan and Christain symbols and beliefs, and got rid of "the sacred feminine" turning Christianity into a male-dominated religion rather than one that honored the life-giving woman. Of course the Church is threatened by these and doesn't want them revealed.
The book starts with a murder in the Lourve, a murder that takes place in such a way that the victim has about 15 minutes to get a message to someone. He uses an elaborate code based on the works of DaVinci as interpreted by Dan Brown, to lead his grandaughter to the Grail. The book ends with everything wrapped up neatly and happily. That's the ending I like. As far as what the book says or doesn't say about the Church--well, I don't believe it is true, so I just enjoyed the book as fiction and let the "lies" go.