The only real beef I had was them changing Sauniere from being Sophie's grandfather to being and adoptive grandfather. It rendered the entire Hieros Gamos ritual that destroyed their relationship moot.
If her REAL grandparents were engaging in the Hieros Gamos, there would be a very understandable attachment to the ritual: THEY ARE THE BLOODLINE.
If you really want to get clever, work in snippets from Hudson Hawk, Dogma, and Eyes Wide Shut. Maybe I should re-edit those films into The Da Vinci Code and see if I can get it to work. ;-)
Obviously, this is a film that some people haven't seen yet, so I edited the title to reflect the fact that spoilers can and probably will pop up during the course of this discussion.
Also, please avoid any talk of where to procure illegal captures of this film. It's still in theaters and I'm sure we'll see a DVD release before the end of the year.