Overall, a very good episode. I think I will rate it tops of the 4 so far. A couple of points, clearly there is some character growth going on with both Devon and Morgan here. Morgan manning up and taking the "ass-man" position at Big Mike's request is a definite change, in that he chose (if somewhat hesitantly) to take the responsibility instead of trying to be the perpetual slacker. Also his treatment of Lester near the end. IMO this is part of the setup for what apparently happens later in the season (trying to avoid the spoiler here).
I thought Chuck deciding to use his own non-intersect abilities to develop the better plan Shaw pressed him for was interesting. Was also a bit disappointed that he didn't flash in the cage when Sydney was putting the beat down on Sarah, and take her out. I really expected that him seeing her treat Sarah that way would trigger a violent (but not gunshot) reaction. After 3x01, where he jumped off the stage to protect Sarah from being shot, this would have been the result I expected.
At this point, I am indifferent on Shaw. He seems to be a good guy (with some baggage, as seen in the closing shot) based on what little we know, but I am reserving judgment until this arc plays out a bit more. It seems obvious that he is there with the objective to force Chuck into being a real spy, even if the means are unorthodox, as in the shootout in the Buy More. Yet, there will almost certainly be ulterior motives for his arrival.
I thought that Casey's reaction to Shaw's order of no backup when Chuck was pinned down was telling. While Casey is supportive of Chuck now, and even looks out for him in ways that never could have happened in season 1, he is still reluctant to show it. Previous such actions were confined to just the 3 members of team Bartowski. That he did so in front of Shaw so soon after his arrival is notable I think. Also the fact that he joined everyone for dinner at the end with Shaw watching says a lot.
Finally, does anyone else think the cover story for Devon's long absence (Casey being drunk and, uh, immodest) will come back to cause further problems/humor later on? I don't think this was a one-shot line, kind of like the Spastic Colon bit that has been a running gag for 3 seasons now.