Was not at all surprised by the true terrorists, though did appreciate the curve that McCann himself was dead and his unit buddies assumed his identity. Classic plotline, and well executed.
If I hadn't read the TV Guide article in which the creator specifically says the answer to "Will They/Won't They" is "They Will, and before the very end" I'd be frustrated by the semi-reset too. But there did seem to be a bit of movement... What's His Face is back in the picture, but Beckett seemed a bit... distracted there even when he showed up.
Liked the quiet blue title screen after Beckett and Castle pass out in the freezer; obviously they'd be rescued, but it was nice and somber nonetheless.
Wonder if we'll see Fallon again? Obviously they wouldn't want to considering the stakes, but Pasdar did a real nice job.