In season 4, Dexter has become completely off his game, juggling multiple responsibilities as Harry pointed out many times last night. This allows the writers to change Dexter, making him much more vulnerable. While that is probably their intent, the new Dexter is in a ways less fun to watch. He may squirm around now, but to me, it's funner to see him toy around with people.
With Christine caught, the noose is tightening on Trinity, but Dexter wants him all for himself. This means if more people get hurt, he won't care, so he frames a truck driver who admittedly was a bad guy, leaving DNA all over the place. I'm not sure how Dexter would think that would be believable in the long run. The Trinity Killer finally making a mistake in a grand fashion only when his daughter is caught seems much too convenient for anyone.
The ending was spectacular as Arthur Mitchell trailed Dexter back to the police station, actually went into the belly of the beast, and then shook hands with Dexter. They're both in the middle of a police station, Dexter has dirt on Trinity, and Trinity knows stuff about Dexter.
The Batista and LaGuerta story was doomed from the beginning and surely having them marry as a political move didn't help. LaGuerta hasn't been so bad lately, but some of the scenes reminded me why I hated her so much. She's a bitch.
Rita is exceedingly annoying and that has been exacerbated this season. Before, she'd show up and do something was Dexter. That was fine, but now she's either complaining or asking where Dexter is, and he makes the same lie every time. If she did not have the background of abuse as she did, I don't think she'd stay with Dexter. She tells Dexter she kissed Elliot, and Dexter doesn't care (other than killing he really doesn't care about anything), so she's upset he doesn't care enough. Later, Dexter punches Elliot, and Rita is happy. That's just great...
Jennifer Carpenter has been extra good this season and makes Deb the only character other than Masuka and Dexter that I like watching. I wouldn't mind the other characters getting killed in a hail of gunfire. It would make a nice storyline for next season, and there wouldn't be any of the ridiculousness we've seen this season.