I hope the Deb/Dexter romance they were suggesting in the TV spot for next week doesn't happen. That's about the worst place the show could go at this point.
I just marathoned the whole season yesterday and today. Hey, I was bored. While it wasn't as bad as I was expecting (season five levels), it has big problems. Namely, Brother Sam was the most interesting character to be introduced this year, and he was offed half-way through the season. Colin Hanks just isn't interesting as the killer (he looks awkward and confused much of the time he's supposed to be menacing), and Edward James Olmos was criminally underused as his Dark Passenger.
Speaking of which, if that twist wasn't obvious to everyone by, say, episode six at the latest, I'll eat my hat. It certainly wasn't the big reveal episode nine tried to sell it as. As interesting as the actual kills have been (not to mention fantastically implausible -- even if Geller had been real there's no way two guys could have pulled of those murders without being seen by a witness or two, especially not in the time allotted) the Doomsday Duo has been the dullest season-long killers up to this point.
Also, I don't know what's going on with the Quinn character, but if the writers think we have any sympathy for the asshole, they're dead wrong. He's just a waste of screen time at this point, and dead weight as a cop. I like the new guy so far, who has been portrayed as confident, but able to make mistakes (i.e. thinking Deb wasn't his new Lieutenant).
The TV spot for next week sure made it look like David Zayas was on his way out. On one hand, that would be disappointing, since even in the midst of all the boring interpersonal story lines they've been handing him he's still the most likable cop (I can't believe two seasons were wasted on his relationship with LaGuerta, only to have it ended off screen between seasons; now we have his never before seen sister suddenly central to his life...remember when he had a daughter he cared about? I know this season has suggested a couple of times that she doesn't make time for her father, but what about in seasons 2-5?).
I don't really see Deb being offed making any dramatic sense; if anything, it would be a practical move, since Carpenter and Hall divorced during season five and it must be hell-a awkward (plus, Hall is an executive producer, and the only character that isn't at all disposable).
The voice over is still horrible (half the time it's Dexter being Captain Obvious for the sake of really, really stupid viewers) and Harry only makes it worse, since he takes over what would otherwise be important voice over, forcing the writers to use Dexter's narration to impart far less essential (or obvious) information.