** spoiler alert ** I was disappointed with this book, especially towards the end. While it was interesting to read about the Masons and fun to read about locations in DC (nice pick of Tenleytown and Kalorama Heights), I found it to be very preachy, way out there, had lots of holes in the story, and not very realistic.
While Mal'akh's twist at the end was entertaining, the holes in his own story didn't make it terribly surprising (he happened to get every detail from Zachary in that one night that he "died" - come on). I also was waiting for Brown to explain what on earth were the "dark arts" that he was practicing, and his failure to explain made Mal'akh's story even more bizarre. In fact, it ruined the story for me because I could never understand what he was trying to do and why all the fanfare was necessary (except for sending the video). Like some others, I also didn't follow why this video was such an issue of national security that someone with Sato's job title in the CIA would get SO involved and be so sloppy (there ARE people in DC on Sunday nights who would manage to see a helicopter dropping people off on the tops of buildings). While I understand that Brown likes to put in a ton of information about the topics he is writing about, I doubt in reality, people would take SO much time in that type of situation talking about it and making others trying to guess at what the answer is (I got tired of Katherine and Peter trying to lecture Langdon). On top of everything else, I think Brown's point that our "minds are God" was hammered home so many times that I nearly put the book down. I get it, Brown, I'm not stupid.