I read the book first, and maybe that was the problem. I may not have believed a word of the content (which, in a work of fiction, is not relevant - I did, however, manage to suspend my disbelief), but I enjoyed it. I though it was well-written, and I liked most of the stylistic choices that Dan Brown made. They're not choices I would use, but that's not the style of fiction that I write, so again, it's not really relevant.
I'm feeling iffy about the use of flashbacks in the movie. That's one of the things that I don't like about books that turn into movies - you can use narrative easily to fill in a backstory, but flashbacks (to me, at least) feel like interruptions, and I don't really dig them. However, these were all little snippets, and done with a completely different look, hence the iffiness.
There were some pieces of the book that I enjoyed which didn't make it to the film, which is an inevitable disappointment with the book-to-movie scenario, but I still plan to finish watching the movie tomorrow.
I think this just proved (again) that if I want to watch a movie based on a book, I should watch the movie BEFORE I read the book. Maybe I'll try that with "Angels and Demons" and see how that works out.