What is it, and what isn't it? It is easy reading and fast moving entertainment. The structure of the book allows the reader effortlessly to keep up with all the strands of the plot. If you want something light to while away a few hours, and like this sort of subject matter, this book will certainly do. And you will also be able to join in 'Da Vinci Code' conversations.
However, if you are looking for rounded characters, original ideas and an interesting plot, this book is probably not for you.
SPOILERS AHEAD
The characters are uninteresting and artificial beyond words. Robert Langdon's personality doesn't extend much beyond being brainy and rather cautious. Sophie Neveu first appears unconvincingly described as a Parisienne but behaving like a New York PA; but this fizzles in the second half and she ends up as little more than a conversational foil to Langdon and Teabing. Sir Leigh Teabing is the worst sort of 'I say old boy how about a jolly old game of croquet' Thirties Hollywood B-movie caricature of a Briton imaginable. Then we have the angry French detective, the bonkers Opus Dei monk, the financially dodgy Catholic heirarchy. All in all, a cast of tired, unimaginative, uninteresting stock characters. You might well be shocked by the prejudiced bad-guy stereotyping of the villain when this is finally revealed.
The basic idea behind the book, the astonishing secret concealed for centuries, has been widely researched and written about, and anyone wanting to read further might start by looking at 'Holy Blood Holy Grail' by Michael BAIGENT, Richard LEIGH and Henry Lincoln - get the anagram???!!?!! It's a great book for anagrams, incidentally. Also, a lot of the geography, police procedure and cultural milieu is either poorly researched or treated with great poetic licence.
The worst thing for me is the utter irrelevance of the whole thing. Even if the secret were to be revealed, it wouldn't actually prove anything. How would it add up to anything more than a few more questionable antique manuscripts, a box full of crumbling bones? And having reached the final page, would it really have made any difference who found the secret?
Oh, and the title above. On page 419, Teabing says "My heavens". I imagine Brown means "Good heavens", but got the idiom wrong. On page 440, Teabing says his new medication "gives me the tinkles". I've no idea what that means, but it certainly isn't any idiomatic British English I've ever heard.
So, as a piece of light entertainment, it is fast-moving, quite well researched though not very imaginative. For a book of its type, 3 stars out of 5.