I'm a huge 'Chuck' fan, but this is the last in an arc of episodes I don't love. The dynamic between Chuck and Sarah after he deserts her in Prague does not make for happy viewing. When Chuck finally becomes an agent, and invites Sarah to accompany him to Rome as part of his team, she says "I'm going to Washington, okay? And I'm going with Shaw." She then explains that she can't be with him because "you're not the same guy that I fell for." When Chuck asks why, Sarah looks at him in disgust and shouts "you killed somebody, Chuck! I saw you kill the mole!" Too honourable to implicate Casey as the shooter, Chuck asks Sarah to believe him when he tells her that what she saw wasn't as straightforward as she thinks. "I don't" she says. Sarah is really cold in this scene, and I found myself thinking "why isn't Chuck fun anymore?"
Sarah's relationship with Shaw is so cold and unconvincing, and she behaves so coldly to Chuck, that she just seems cold all over; miserable and angry and unpleasant. We know she's not actually like that, and at the end of the episode when Casey confesses to killing the mole, her face lights up and she's back to her old self, ready to run away with Chuck and be happy. However, what doesn't work in this story is her inexplicable attitude to Chuck. I get that she's hurt that Chuck chose his spy life over running away with her in Prague, and she's genuinely afraid that he's becoming a hardened CIA agent, but even if he becomes the toughest, coolest spy in the CIA, he's still no worse than Shaw, or Bryce, or Sarah herself.
Last season she executed someone who threatened Chuck and his family and friends. Chuck didn't understand how she could be so cold-blooded, but she explained that it's what she's trained to do, and it was necessary to protect him. Now she won't offer him the same understanding. She's outraged that he apparently shot someone, and won't believe him when he asks her to trust him. She won't even look him in the eye. In Season 2 Episode 12, she's angry with Chuck because he's not coping with the spy life. She shouts "I don't know what's happened to you, but this is our job! [T]o protect...the country and anybody else who needs protecting. We do whatever it takes no matter what! Did you forget that?" Chuck is not actually a spy at this point in the story, but an asset. He's never had spy training and he hasn't made any promises to the US government. And yet he's expected to have the same devotion to duty, make the same sacrifices and take the same risks as Sarah and Casey. In Season 3, now that Chuck is officially a spy, Sarah seems to despise him. I don't find it persuasive, and I don't think it makes for good viewing.
Fortunately by the end of the episode, things pick up, and before long Sarah is cute and fun again, and Chuck is Chuck. Shaw is much more interesting as a bad guy (I never felt it was plausible that someone essentially the same age as Sarah was supposed to be her superior, so high up in the ranks that he can issue orders, remotely take over commercial aircraft and decide with full authority whether or not Chuck qualified as a "real" spy). The ensuing drama is compelling rather than awkward. I just wish they hadn't wasted so much on this multi-episode diversion, in which Sarah is unappealing and mean, inexplicably attracted to the impossibly handsome but desperately boring Shaw, and Chuck is a bit lost, having a brief fling with the irritating Hannah and vacillating between loving Sarah and being totally relaxed about her relationship with Shaw.
One last thing: I find it implausible throughout this episode arc that Shaw, Sarah and Chuck use the term "spy" so frequently and in so many contexts. They rarely refer to themselves as CIA agents, which sounds more realistic. Beckman, Chuck, Casey and Sarah all refer to Chuck as a "real spy." When Chuck can't flash anymore, he says "I'm not a spy anymore." Beckman tells Sarah to make Chuck into a "real spy," so Sarah tells Chuck "if you want to be a real spy, you have to act like one." Chuck says "I am a real spy," and Sarah says "a real spy would have flashed [and] been able to defend himself." I'm pretty sure "real spies" don't actually refer to themselves as "real spies" this often. It sounds amateurish and cartoony.
They also have a lot of dumb rules about what a "real spy" is and isn't. Sarah tells Chuck "You're a spy now, Chuck. You have to keep your feelings to yourself." Carina says "spies don't fall in love," referring to it as the "cardinal rule of spying," before telling Chuck to "go be a spy." Later, Sarah says "Spies do not have feelings. Feelings get you killed. You need to learn to bury them in a place deep inside." (Of course, anyone who has ever watched a romance comedy knows that burying your feelings in a place deep inside is exactly not what you're supposed to do: you're supposed to express your feelings, be spontaneous, live in the moment, stop the wedding, say those three little words, get the girl, etc.) Chuck later agrees "You're right, I'm not a real spy. I'm emotional and that makes me a liability." The cliches don't end there. Sydney says "spies don't say please," Shaw refers to covert ops as "the spy business," and insists that if Sarah and Casey help him out "he'll never be a real spy" (which is ridiculous) and that "until you start flashing again, you're no longer a spy." When he wants to destroy the Castle with Chuck in it, he tells Sarah "you have to think like a spy" and Sarah says "I am thinking like a spy." The all use terms like "spy-life," "spy-proofing," "spy test" and "spy-related," and I've lost count of the number of times they say "real spy," "perfect spy" and sometimes "true spy" and "full-fledged spy." Later, Chuck makes Morgan an unofficial spy, and the word has finally lost all meaning.
That said, I actually love Chuck, and the episodes that follow this are amazing.