I've found this season of Dexter to be full-distinguished mentally-challenged fellow. It doesn't fit Dexter's character progression and the show has too often forgotten its own plotlines and history. Right now it feels like they stuck their hand into the bag of forgotten plotlines and pulled out a few at random, and stuck them in a season with a villian plotline that the show barely cares about.
Like the evolution of Harry is sort of the line to follow for how bad Dexter has gotten. He was once a memory that came to Dexter. Then he started to become a voice in Dexter's mind. Then he become like the holy ghost speaking to Dexter about the sacred code. By the start of this season, Harry is like the good angel telling Dexter to go be popular even though it doesn't fit Harry or Harry's code at all. Now his brother is back as the devil on his other shoulder. It's not an evolution of Dexter as a character, but just the manipulation of a ghost character for the purpose of stating inner thoughts, often extremely obvious thoughts that don't need stating.
I also find it weird how people hate s3 and s5. I find it weird because the only good seasons were maybe the first two, but at least the third and fifth season offered a meta commentary on the audience's relationship with the show. They both inserted a character into the intimate moments of Dexter's dark passenger side and offered two interpretations of the outcome of these events: 1. A dark desire upon the other to kill that is finally released but only feeds a furthering desire to kill. 2. A need for a sense of justice in a world without it, but no need to kill beyond that.
I found that entertaining or at least interesting. Everyone else seemed mad that Dexter was cheating on them with someone else during their intimate kill moments.