In one early scene, young Ryan, played by Chris Pine, who weighs maybe 170, overpowers and drowns a 300 pound Ugandan professional killer. That's one of the more realistic scenes.
Then again, this is an adventure film, in which such outcomes are standard fare.
Surprisingly, given the weak plot, the dialogue is actually pretty good, though the best lines are given to Kevin Costner, as Ryan's CIA boss, and Kenneth Branagh, as the Russian bad guy.
Costner has never been a great actor; he always pretty much plays himself. But that persona is good for certain roles, and this was one of them.
Branagh, now that he's middle-aged, looks intelligent and tough, and can affect a grim enough expression to play a passable villain:
(Branagh directed the movie as well.)
Keira Knightley is as beautiful as ever playing Ryan's girlfriend/fiancee, though she is constantly pushing her mouth out the way she always does; I guess she thinks it makes her more attractive:
At one point, Branagh, intent on seducing Knightley, says, we could make chitchat, or we could talk. When she subsequently says something devastating to him, he replies, "Now we're talking." (I'll have to remember those lines.)
The character of Jack Ryan is essentially Rambo crossed with Sherlock Holmes, so he ought to be played by someone who appears at least smart or tough, preferably both. The young Alec Baldwin was good in the role.
Chris Pine makes a game effort, but unfortunately, he looks neither smart nor tough. He looks more as if he just stepped out of an Abercrombie & Fitch catalogue. (He was probably better cast as a drag queen in Surrender Dorothy.)
I was struck by his resemblance to Denise Richards:
Despite all of which, the movie actually isn't bad. It's fast-paced, there's plenty of action, and there are some good lines.
If you're good at suspending disbelief, you'll enjoy it.