I haven’t read “The Da Vinci Code” and have no intention of doing so. So I’m not qualified to respond. However, I went to the official Opus Dei web site and did a search to see what they say about it. Click here to get Opus Dei’s list of links about “The Da Vinci Code”.
I am skeptical of any book, however, where one of the main characters is an Opus Dei “monk”. That alone indicates that perhaps the author’s “meticulous research” into Opus Dei wasn’t quite as meticulous as he claims.