There was nothing original about the investigation, a kidnapped little girl, but I thought the collision between Castle and Beckett's ex-boyfriend could be interesting. Their rotating triangle was entertaining to watch but I think the relationship between our two favorite detectives wasn't developed enough to make us care about what could happen between Beckett and her ex. Their story wasn't even surprising even if I'm sure some people should be able to relate to them. Moreover the awkward situations and dialogs weren't as funny as before and I can't even remember laughing. Only Martha got my heart again and I also liked Alexis explicit reference to Lewis Carroll's work and The Matrix. However Castle's deductions are easily predictable considering they mostly happen when he's with his mother or daughter. I think the writers should found more creative ways for these sparkling moments. About Martha what she said about mistakes and wisdom was inspiring, that they are its building blocks. So between two jokes we also learned a few things about becoming our own life coach.
But even if the story itself was nearly stereotyped, like the Nanny McDead episode one for example, I admit that the ambiance was intense at times. However I think the writers should have focused more on the father because his profile had potential, a failed painter. Also like in Home is Where the Heart Stops, the 7th episode, the end was rushed and I almost thought I blacked out for a few minutes. I also would have much appreciated an unexpected ending for once because the very first minutes I knew how it would end. An other disappointing element was that the characters never mention past events. It's like the episodes weren't link so it prevents the viewers from really caring for Castle and Beckett. It's apparently specific to the show because other procedural productions like CSI: NY better handle such an episodic format. The references to Castle's career as a successful novelist are also far too anecdotic. One at the beginning, an other at the end. What about mixing his fiction to his real investigations with Beckett ? She could be his character Nikki Heat in his mind at times for example. He could fantasize about her and that would lead to some surreal and hilarious moments.