Angels & Demons, the first book written with character Robert Langdon, is not a prequel of The Da Vinci Code; Da Vinci Code is a true sequel to Angels & Demons. And an inferior one at that, both in novel and film. Not that the film Angels & Demons was any great work, but it's source material was much more tailor-made for screen than it's predecessor. Er, successor. Er, something.When it comes to how so many people I have encountered inexplicably either think The Da Vinci Code book is better than Angels & Demons or the same book is beyond me. Perhaps a clue can be found in the order in which the novels are read. I won't say definitively that every person (let's say my sample size is about 10 people at this point -- in other words, statistically irrefutable so don't even try it!!!) falls in this category, but I found that 9 out of 10 preferred whichever of the two books they read first. The only circumstance I can recall where the audience tended to prefer whichever they saw first was between Austin Powers I and II; in that case, the audience didn't like the second as much because it was mostly the same jokes over again.
I can totally understand that case, but it baffles me where the two Dan Brown books are concerned. You have some common elements -- the church, conniving priests, and mysterious symbology that leads our hero Langdon on a time-intensive desperate search. Granted, the books are similar in this regard, but these are common themes that are expected. Langdon is a friggin' symbologist. This is what he does. It's the formula Brown is using. To expect him to do otherwise would be to expect Indiana Jones 5: Courtroom Drama!
And after that, all the similarities subside. There is science-fiction, more murder and mayhem, more danger, more action, and better pacing in Angels and Demons. Ultimately, The Da Vinci Code is a story about finding the truth, whereas Angels & Demons is a thriller about a race-against-time to save the Vatican from a technological time-bomb that reveals to be a power-grab maneuver from multiple parties. So when people (say of the 5 that liked Da Vinci better) say it's "just the same stuff all over again", I wonder (a) did their parents beat the sense out of them and (b) did I leave the iron on this morning? The answer to both is usually "yes, sadly".
Angels & Demons is a worthwhile, fun and riveting read, but I can't say it fared much better with me at the theater. I can understand (as I have a keen understanding) how The Da Vinci Code would fall short as a film -- it's not exactly a thriller book. But all the potential made me somewhat bitter as I slowly became bored with the film version of Angels & Demons. It's not that I have a problem with Tom Hanks' hair (problem solved in this one!) -- but more of the editing and direction. Historically, Ron Howard has been a drama director (Apollo 13, A Beautiful Mind, Backdraft, Frost/Nixon), and the only thriller on his list that I can see is Ransom, although I think that's again mostly drama -- you know who the kidnapper is most of the way through. This film doesn't excite, and it should. I mean, who isn't excited about priests getting murdered? Who??
In short, your scoring guide, and only reference you'll ever need, for Angels & Demons is book: A, movie: C. For Da Vinci Code, book: B, movie C.