We watch the movie the "Da Vinci Code" today and thankfully, Ron Howard tried to stick to the book. Though I know that it would really be difficult to include everything from the book to the movie, I think that RH still manage to capture the book's essence. However, I also believe that a full appreciation of the movie's storyline would be more felt if the viewer had read the book first.
I've read a lot of the critics' reviews and most were not favorable to the movie. I guess we now have to leave it to the general public as to whether the movie exceeded their expectations or it was a dud for them...