Blood will Flow

I'm honestly not sure how I feel about this episode - apart from the fact that both Jensen and Jared where exceptionally well lit and bearded and damn fucking attractive, but then that's not quite enough to really cut it, isn't it?
I'm quite flabbergasted by the fact that I really really liked Cas in this new assertive, witty, intelligent 'Russian' (hahaha) variety for the first time in AGES. And he had something useful to do, even if that meant Sam had to be sidelined. And I concur wholly in your feelings about him feeling like an extra to his own story and him having been about to tell Eileen that their friends with benefits relationship (that they clearly had before she died and that I liked a lot, because it was two grown people taking what they needed from each other without having expectations for it to go beyond that, considering the lives they lead. I sure hope that's what they were going for, because establishing her as a love interest either to fridge her (again) or fascilitate that picket fence life for Sam, just won't fly.
About Kane... ah, I really don't know how I feel about that. I didn't mind the singing because I literally forgot that Dean is not supposed to be able to hold a tune (though maybe the practice he got in Deamon times helped fix that? Idek) but I see what you see in places, though it wasn't as jarring as all that to me, maybe because I've been looking at the whole show with a more meta eye since this season started. I'm still not sure they'll figure it out, since we seem to get one step forward two steps back every other week and there's not that many episodes left. I'm still holding out hope that the boys will put their foot down on an ending they can subscribe to and since they know their characters best. But if I'm quite honest, the reason I'm looking very serenely down the line is the fact that I don't even know WHICH ending I'd prefer... the Thelma&Louise moment, the settling down curtainfic moment or something wholly unexpected and surprising. Idk. Thing is, the show has been bigger than the sum of its parts for more than a decade now, and whatever they do, fandom will come out with a better, worse, different, all corners of fandom and shipdom kinda version, so I'm actually not really worried. The show isn't everything we get to see on screen, it's us, and if they really truly fuck up, we'll just fix it, literally. I don't know if that's satisfying for the people who're not in the community and will just have to take canon as it stands, but hey, if the ending really gets screwed up, at least fandom will be alive to bitch about it for another fifteen years *g*.