The fact that the book deals with something with a historical stature as Holy Grail is reason enough to read the book. Dan Brown is a very convincing author in that he puts the reader in a position where he/she cannot distinguish craft from fact.
The author has consciously drawn the plot over two continents and placed settings in three countries. The protagonists, Robert Langdon remains An Alien American in Paris and Sophie Neveu the Svelte Madmoiselle. However, the Knighted antagonist is too hollow a character.
Bringing in the Vaticcan and mysterious Christian organisations adds spice to the Holy slice. The involvement of Interpol and French police does the seasoning part. The book should definitely suit most palates.
Further the Nature worship looks appealing enough for a liberated mind to grab the book and read it. But aftereffects are definitely not guaranteed.
Strewn with intriguing fantasies like the PHI, Fibinoacci series, Rose line, Priory of Sion and with the title having the master himself, Da Vinci the book is worth a read.