First thoughts after viewing this one... It wasn't bad. It wasn't great either.
I liked how the intro music (was that AC/DC again?) shifts into the Impala's radio as Sam's driving her and he then switches it off, as if it just reminds him of Dean. He's looking pretty rough with the facial hair and looking as if he hasn't slept in ages.
I liked how he and Mary had more interaction. I know that was a real complaint when she showed up again in season 12 (and yes, it seemed most of her scenes were with Dean back then) and I really would have liked to have seen more interaction between them, so it was nice to see it here.
I was a bit disappointed that he didn't have much interaction with Jack, though. I felt for Jack, being so frustrated that he couldn't help them out more since he no longer had his powers.
Speaking of no longer having powers, I feel like I missed something from last season's finale. Nick (Lucifer's vessel) survived? Back when he was first Lucifer's vessel in season 5, there was a point where his vessel was deteriorating. I guess being in the cage in Hell somehow revived the vessel? Maybe I'm just confused and it's been too long since I've rewatched the older seasons but I have to admit I wasn't expecting to see Nick there.
As for Michael, Jensen did a good job and it was pretty chilling the way he seemed willing to work with a vampire there at the end.
Is it me or did they not show a preview for the next episode? The "stay tuned for scenes for the next episode of Supernatural" promo was there at the end, but they just showed commercials for other shows instead. :/