Well, that was fun. Watson's first case! And it was a pretty clever mystery -- I didn't figure it out until they started explaining it in the interrogation room. My working theory for why the husband killed the woman on the subway was that Callie left him for her
the first time. I thought they couldn't find a connection between him
and the victim because the connection was to Callie instead, that she'd had an affair with the woman and he was taking revenge. But the actual explanation was very clever.
I particularly liked how in the interrogation room, when Watson was telling the guy what had really happened, she was basically imitating Holmes. For a moment there, Liu came close to capturing Miller's delivery. ...Although come to think of it, I'd rather not see that become the norm. Watson should be distinct from Holmes, a complement to him, not an echo. So it was fun to see from both a character standpoint and a performance standpoint, but I don't want to see it become a regular thing.