Okay, first the Stargate geek in me squeed when I realized the guy in the beginning (the lawyer) that bad Charlie beat up was played by Paul McGillion, Stargate Atlantis' own Carson Beckett! Whoot! He was also in season 5 of SPN...he played the friend of Cal (the James Dean fan) in Fallen Idols. Oh and another repeat guest star from SPN played the Wellington guy that Dean was trying to protect. I think he was in season 2's Tall Tales, the professor who fell out the window in the beginning. At least it looked/sounded like him.
Honestly, I've always had mixed feelings about Charlie. I was never all that impressed with her, but she did have some good scenes now and again in her episodes. But I have to say I liked the scenes with her and Sam together. In the past, she's been paired up with Dean a great deal, so it was nice to see more of her interaction with Sam. And by that I mean Good!Charlie, of course.
I also liked the brother scenes quite a bit in this one. The one in the beginning in the bunker with Dean cooking for them again...aww. Egg white omelette! Hee. And Sam's reaction to them, thinking they're awesome, while Dean hates them...LOL. And Sam showing how he's still concerned about the Mark and how it's affecting Dean. We can still obviously see that it is still a problem.
The whole Oz thing I never really bought into, it seems a bit hokey to me, but I won't begrudge anyone who finds it interesting. A bit weird how the Wizard had Charlie divided into two and embracing her darkness, or whatever that was. And no, I really don't think it's a coincidence that Bad!Charlie and Dean were paired up. There was an anvil-sized parallel there I believe. Speaking of which, it stung when they first encountered her in that house and she referred to Sam as the albatross around Dean's neck. But I had to remind myself that this is Bad!Charlie talking. And really, the way I see it, in a twisted way, she's right. But only in the way that Sam is a big part of keeping Dean from going totally nuts from the Mark. It's a good thing, and I think Dean knows that. He wants to be rid of the Mark. From the moment at the end of 10x09 when Sam found him after he slaughtered those people, and then last episode when he had that talk with Dean before he went to meet Claire. And even in this episode, when he brings the wounded Good!Charlie outside and yells at Dean to stop beating up Bad!Charlie. Sam is influencing him, at least to some degree...
...Which brings me to this. I LOVE...love love love...the end after Charlie leaves and Sam asks Dean if he's alright. He tells Dean he'll find a way, and then "WE will find a way." Sam, I heart you so much. :D And Dean says let's get to work. I love seeing our boys on the same page and working together. :) It looks like they have a lead and maybe will try to seek out Cain. I guess we'll see.
So yeah, even though I was never a huge fan of Charlie and the whole Oz thing, there were elements of this one that I really liked.