Despite the show's quality taking a turn, I still think it's one of the more enjoyable shows on. It is no Breaking Bad by any stretch, but it still does interest me enough when it's on.
I agree that seasons 5 and 6 aren't as good as the previous seasons. I would also say that season 4 was the peak. One of the major reasons is that the whole excitement of DEXTER is the question, "Will they find out he's a serial killer?" That means Dexter needs a 'secret identity'. By losing Rita, Cody
and Astor, the only person left is Debra and the rest of Miami Metro. Harrison's too young, so he doesn't count. Now, the Miami Metro is interesting, but nowhere
near as exciting as the concept of Deb finding out. If they kept Cody and Astor, the show would be vastly more entertaining. That's what drove season five; Cody & Astor + Debra. And that's why season six is lacking. That's why when he's on the trail of the Doomsday Killer we're not getting excited despite the killer's flamboyant murders, because we know DDK won't kill Dexter, so the only question is, "Will Dexter be found out?" But by whom? Deb. That's why I think I (and it seems the writers too) are going on the premise of a cop killer. So the story can really drive into the heart of what's left of the show.
Regarding BREAKING BAD — I'm waiting for season 3 to be released on dvd over here. It hasn't and there seems to be no release date. Which is annoying because I love that show and I know it's only a matter of time before the whole thing gets spoiled for me because "that happened two years ago, Bass".
It's not even the best show on Showtime anymore, which is saying something.
I think what that says is that the quality of Showtime in general is improving; I love CALIFORNICATION and NURSE JACKIE (wow!) but I've not HOMELAND which I've heard good things about. Despite the problems I mention, DEXTER is not a bad show. It's pretty good. And it's problems are easily solvable by three possibilities: bring back Cody & Astor, skip ahead a few years so Harrison is a character, have Debra find out Dexter is a serial killer. Any of these three would push the show back to the level of interest in experienced in it's first four years.