I'm kind of liking crazy!Sam. I haven't found his character this interesting since he was drinking demon blood. I also love the fact that Lucifer is back, even if he is just in Sam's head. It doesn't quite make up for the loss of Castiel though. There's no way he's dead. No no no no no. No. Only, I don't know, because it's kind of looking like his vessel is dead, it was certainly not looking too good the last time we saw it, and though we only actually saw Dean fish his coat out of the water, if his body is still in one piece it won't be for very long.
But Castiel in another body wouldn't be right. Misha Collins is what makes the character so awesome. So we need not only for Castiel to have survived the Leviathan attack, but for his vessel to have survived what happened to it. It's possible. The Leviathans left his body to get into the water supply, and if Cas himself survived their initial attack and way just laying dormant somewhere in the back of his mind, their leaving would have freed him to lake over again, and his presence could allow the body to survive. But he might not be strong enough to come back yet. And also he probably feels pretty crappy still about the whole being God thing. So he's laying low, recovering and biding his time so that he can come back later in the season. That's my theory anyway, because I refuse to accept that he's dead. People don't die in Supernatural.
Actually, that's blatantly not true, but they have a much higher chance of coming back than in real life. Plus, Cas is an Angel, that's got to count in his favour. Plus we didn't see a body. He's definitely not dead. I hope.
The ending was a bit...dun dun DUN, wasn't it? Sorry, but there is even less chance of Bobby being dead than Castiel, I don't get why Dean and Sam were even worried. (now watch me be wrong about that!) But how far away was Sam supposed to have been when Lucifer took him on his little trip, becuase when they got back a fire had clearly destroyed the house and then burnt itself out, and that doesn't happen that quickly. Time seemed a bit messed up there, the whole thing didn't seem right. After all, Bobby was at the local hospital, he was going home to meet Sam and Dean. If they'd been a five hour drive away, surely they'd have mentioned that. And also, Sam was already in the warehouse or whatever it was before Dean set off, and he and Lucifer couldn't have been hanging out there that long before Dean arrived. I dunno, sempt wrong.
Good episode though, except for the thing with Cas apparently being dead. (he's not!)