Just got through watching Angels & Demons, basically filmed as a sequel to the The Da Vinci Code, which was actually the second book written. On the positive side, that means if you missed (or skipped) watching the code, you won't have trouble following this film in the least.
It carries that rapid pace, oft' times so difficult to achieve in writing, while creating a very thrilling mystery you just can't help but watch. The ending is also one that (ofc) shakes the Vatican to its core, and as anyone whose ever watched some Star Trek is likely to recall, what happens when matter makes contact with antimatter is explosive stuff ^_^.
The only thing I can complain about, is that the film gives away the ending well in advance... if you are keen enough to be paying close attention in the first place. A bit of knowledge about psychology, as it impacts the kind of stuff we do over in SAS, also helps a sharp mind to combine inductive and deductive thinking, to narrow the possibilities down quite considerably. That being said, if you didn't pay close attention, you might be shocked silly at the finale!
Hey, I'm a geek, my attention span has moments of hyper-focus on minute details all day long. Gotta love programming :-P.