I agree completely with CelticMoon. So much was changed to fit a hollywood budget film...Max Koehler missing, Carmelengo not biologically related to the pope, Vittoria not related to the researcher, no love interest between Vittoria and Robert.
Last issue just with the acting...the deep seeded connections that were in the book gave way for more intense emotions and connections between the people. I just felt a sense of urgency from everyone, not the hatred, helplessness, and other feelings that made the book so fantastic. Just never got sucked in like the book.