I was so unimpressed by this episode. Nothing really connected with me. It wasn't that I thought it was bad, just bland.
As for the continuing story of Dean and Sam, while I was pleased to see that several of my points (that Dean actually started this mess, that Sam didn't intend to start the end of Days by killing Lilith, just as Dean didn't plan to start those events by selling his soul), but I hated how they handled it.
Out of the blue Dean realizes that he is just as guilty as Sam. Sorry but why did he suddenly realize this? All we have seen is his harping on his brother , we have seen no doubt about his own role.
There should have been a catalyst and I don't think Sam telling Dean one of the reasons he went with Ruby was to be empowered away from Dean is going to cut it. Because Dean already new part of what happened to Sam (especially towards the end was the power), that isn't something new.
It didn't feel like a legitimate revelation. It felt tacked on. I really didn't care for those that scene (I loved Sam walking in on Dean, and I love how Dean treated Sam (both I found very believable). But I think it really should have taken Sam (or Bobby or even Castiel, as they both know what started it) truly telling Dean what he did. Where was Sam telling Dean you were the one consorting with demons long before I ever did (in fact Dean is the very reason he did in the first place). that it was Dean's meddling that started the chain of events that they had control over. Not Sam.