Angels & Demons was far, far, FAR better than I thought it was. I didn't read the book, am no great student of Papal history or Christian symbols, but I actually enjoyed this movie.
The storyline is this: The Illumaniti, the Vatican's ancient foe, appears to be lashing back after hundreds of years of silence. A pope dies, the shortlist of probable successors are kidnapped and executed in gruesome ways, there is a ticking anti-matter bomb waiting to blow the Vatican and a big chunk of Rome to kingdom come, and a clever Tom Hanks is flown in to follow the clues.
Sure there are lots of plot gaps - Hanks and the bad guys seem to understand each other a bit too perfectly - but this is a slickly produced and executed blockbuster with some pretty good actors.
Movie snobs will probably mock me for this, but you can do far worse than Angels and Demons for action, plot, acting, and overall movie production. This is a solid three, and maybe four star movie.