The book was a 3.5 star for me and decided to round it upward. A considerable portion of the story was predictable, but it still made up to be a good read. As usual, you will enjoy this books if you like symbolism, history and art. 
 Things that I liked: 
 - Good background investigation with only small alterations that will only disturb 'techies of the area'. 
 - Brings up a valid problem that is surrounded by ethical and religious controversy. We do know that it can happen, but nobody dares to touch it openly and seriously. 
 - Brown's usual level of interconnecting story lines and intricacies make the reader go on. 
 Things that I didn't like: 
 - I accept that the professor is not a geek, but Sienna is supposed to be a new generation genius. She could have solved half the books mystery by walking in to a netcafe or buying a cheap smart phone. 
 - Even for the time of it's publishing, the Turkish political environment was unrealistic. Given all the details everywhere else, that part felt like a fantasy book.