We get to see more of the Captain in this episode, which is definitely a good thing because more or less, he was the only character belonging to the team who hadn't been given more depth. In this episode we get to see him stand up to a rich and powerful senator (the part where the senator threatens to give his commissioner a call and the Captain replies "tell him I could use a raise" was great!), and to really care about the human element in one of his old cases. He is all for investigating the case until a proper conclusion is reached, even though it's painful for him, as it means he made a mistake in solving the case the first time, and he needs to confront the family again and come clean about it. He does all that, escaping from the usual cliches of the genre, where the chief of the department is all about politics and career moves. It's refreshing and I like him much more now.
Castle's mom delves deep into the secrets of online communities, which is actually very funny to watch. She meets her old highschool sweetheart and arranges a date with him. Wonder if he'll turn up in the next episodes! Also, there was another hint in this episode about the case with Beckett's mom. It's obvious by now she has come around and wishes to have that case solved. Castle understands that, but after pissing her off in the previous season to the point where she almost never talked to him again, he's not going to make the first move. I think the time is ripe now, for Beckett to reopen her mom's case and Castle to help her solve it.