The movie itself isn’t bad; it’s arguably among Affleck’s more successful films. It seems, though, that whoever adapted the screenplay didn’t have the same version of “The Sum Of All Fears” as I did, because there were only a few things that matched up: the title, the primary characters, and the presence of nuclear weapons. The shift from Denver to Baltimore feels arbitrary; the connections between Ryan and many of the other people in his life are completely altered. Neither Affleck nor Harrison Ford captured the essence of Jack Ryan—Ryan isn’t an action figure; he's a thoughtful person struggling with deep insecurities, yet still managing to be heroic because he feels compelled to be. To me, Baldwin came closer in “Red October.” If you haven’t read the book, the film is acceptable enough, but if you were hoping for Clancy’s narrative, you will likely feel let down.

Source on TMDB