I LOVE Castle. It is what I think of as "murder lite", with mystery, romance and humor thrown in on most of the episodes. Every once in a while you get a real twist, like Javier and Lanie, and Kate actually showing Castle a little caring. I agree it's great that he broke up with Gina--too many angles--but I liked that Kate didn't rub it in and actually made a quiet exit when she heard him breaking up.
The flowers at the end were a nice touch, too--something sweet and unexpected, as was her invite to the fast food wagon (or whatever they call it). It's funny, for all their bickering and bantering they DO have these moments of compassion, even tenderness--Castle not only saving Beckett in "Boom!" but showing her a quiet respect for her privacy,even though it was hardly the time: Beckett holding Castle's hand when he realizes that the triple x murderer has let him go just so that Castle can see him kill again and again and torment him: Castle gently pulling Beckett back from her frenzied attempts on lifesaving to find the person who put out a contract on her mother.
This series is fun BECAUSE it has these diverse emotions and viewpoints.