I read Da Vinci code at a time when I did not want to think about anything, was alone in a hotel when a meeting finished too early, and wanted a pure *fiction* book.
Put it into these categories and its a decent read. Other than that, I can't imagine what made it reach the #1 list! Its like just any other religious-conspiracy-finding-treasure story!! But interesting 'cus I didn't even know about Mary Magdalene being a Hindu, though convent-studied.
In fact, a few months ago, I read the much-earlier-written, the Gemini Contenders by Ludlum. Both of them are absolutely similar books. Ludlum is talking about hidden documents which say that it wasn't Jesus who was crucified, Brown talks about hidden documents which say Jesus had children.
The only thing the book did was want me to go visit Paris again.
All the inconsistencies you've mentioned about Paris are making me sick, though.