Yeah it was a terrible concluding season. It played out like any other season of Dexter and was very anti-climactic up until the last 2 episodes. Introduce a bad guy/good guy, kill them off, introduce another one and kill them off too, throw a last minute serial killer in at the end that you never got to know as a character and call him the big bad guy. The only branching story arc was Vogel calling Dexter a psychopath while he tries to bang Hannah who I never liked in the first place.
What I was really hoping for was that there would be investigation into Laguerta's death that would have them hunting Dexter by half way through the season, and end it with him doing his usual shit trying to escape maybe with a good nemesis (like Trinity) foiling him and fucking him up at every turn. I really wanted to see everyone's reactions to finding his true identity, you could get an insane amount of good drama and action just by revealing who he is. I find that the best parts of Dexter are when he is about to get caught and is playing cat and mouse amongst his own peers while still trying to catch some nasty killer.