The titular Jack Ryan is ably played by John Krasinski, who's a lot more buff than he was in his Office days. He does the "everyman" thing very well although, as it turns out, Ryan isn't exactly your average Joe. He's a former marine who has a doctorate in economics which he uses in his present job in the counterterrorism department at the CIA, to track the money supplies of terrorist organizations. At first, Ryan seems a little too good to be true: brilliant, skilled, idealistic, and principled- he even bikes to work at the CIA- he's not too far off from what his previous employer calls him: a "self-righteous boy scout". Fortunately over the course of the series, Ryan's character is fleshed out and given more depth. Gradually we find out more about the helicopter crash which ended Jack's military career and still haunts him- and discover it occurred because of a decision he made. We also see his idealism take a mauling as it becomes clear that tracking down a ruthless and deadly terrorist means doing things- and dealing with people- which are morally questionable.
Jack's new boss Jim Greer is a good foil for Ryan. A military man who has been relieved of his command in the Middle East under murky circumstances and demoted to a desk job at the CIA, Greer is no boy scout. Cynical and pragmatic, he is interested in getting the job done and has no time for- or interest in- playing nice with people who get in his way, whether that's his underlings or his superiors, and this doesn't endear him to either group. He and Ryan butt heads several times during the pilot episode and the argument they have over freezing Suleiman's finances is a good distillation of the differences in their outlooks. Jack argues that they should shut down the terrorist's accounts immediately to prevent him from using the funds to perpetrate a 9/11-style attack. Greer refuses, saying that freezing the account will alert Suleiman that they are on to him; they will lose their advantage and miss the opportunity to apprehend him and all his henchmen... the Coventry conundrum.
All in all, Pilot was a successful series opener- introducing most of the major characters and setting up a compelling plot. The beauty of it being a multi-episode show rather than a two hour movie is that it gives time to slowly unravel the story and reveal the characters' history, motivations, and intentions little by little and after this premiere episode, I was invested enough in the people and plot to continue watching Jack Ryan.