Were you surprised? I was surprised. (If by surprised I really mean Jess showed up and started talking and I was all like, Hmmm...who's MO does that seem like? Lucifer, maybe?)
Honestly, I was expecting them to go there far sooner than they actually did, but I'm still a little disappointed that they did. Good brother vs. bad brother. Sounds like a treat.
(and still, in the back of my head, is the little niggling feeling that they made such a big deal in the early seasons about love and sacrifice that something v. bad is coming. Whether that's Dean killing Sam or becoming Michael's meatsuit or some as of yet unthought of torment.) ETA: OOOH! Or what if Sam has to choose to let Dean die to stave off Lucifer? (although I think that kind of role reversal is a little beyond the writing that's been happening the last couple seasons.)
See that hope that I had with the first two episodes (and it was bonafide hope, people) that S&D would start to be ok again eventually and that I'd enjoy my show again instead of seeing it through simply because I never know when to let go and hang on far past the point of sanity is starting to fizzle some.
At the same time, look at how many times Sam has tried to run only to come full circle back to Dean. He has an elliptical orbit. Hell, look at Scarecrow. They were apart for how long before Sam came and saved Dean's ass?
And Sam getting demon blooded and then being strong made me happy happy, as did him telling Jess/Lucy that s/he was wrong, that he could change.
I may have more coherent/meaningful thoughts upon rewatching.
Sorry to be such a downer about it.
And see, this is why I should post reactions when I have them, because the last two weeks I've been all hopeful and happy with the show, and now I'm. Not really unhappy, really. But liking something and not disliking it are two very different things.