What did you book readers think of Angels & Demons(movie)?

Around late 2006, I was hearing buzz of this book that had been a best seller, about to be a film. So I go to Wal Mart and purchase a paper back copy of The Da Vinci Code. I read it and fell in love with it. I seen the movie, I was fairly disappointed but I had to be realistic, if they packed every detail of information into the movie, it would last forever. So after doing research I found that he had written 3 other books. One day I was traveling through a flea market and came to a stand that sold the books and I found all of them for a dollar a piece but I never got around to reading. Then this year as I was hearing more and more about Angels & Demons I began reading(also ordered the hardbacks of all his books). I felt Angels & Demons was a better, more interesting book. But I didn't stop there, I read Deception Point right after, and now I am in the process of reading Digital Fortress. Anyways, I just got the chance to see the movie for Angels & Demons and I have to say that this is the most disappointment I have had in a very very long time. They completely changed most of the book, leaving out key characters, changing key scenes. It was nothing like I had pictured. The anti-matter scene was supposed to be confidential between Kohler, Langdon, Vittoria, and no one else yet Kohler was completely missing from the movie(that I am aware because I found it rushed at points I didn't quite comprehend it). The plane that flies at incredible speeds was never explained. The guy who was in charge of counting votes never explained to the camerlengo that the Pope was his father. Langdon didn't go up in the helicopter and have to miraculously escape death. The hin was completely different and never took Vittoria hostage. A lot of you will probably not get this statement but I grew up with this and this is the only example of how disappointing I can think it to be. I put this movie in the category with Teenage Mutant Ninja Turtles 3. I grew up with TMNT and loved the first 2 movies and was so excited and when I got to the cinema it was like the biggest WTF moment I can recall, that is, until I seen this movie. So anyone else got any opinions on it?