This storyline is played out. It's a cliche of the Supernatural Universe, one the current writers keep rehashing over and over again.
Yes, Sam drank Demon blood and kept it from Dean. It changed him, he couldn't see it, he and Dean fought.
Sam went through the trials, it was nearly killing him, Sam couldn't see it, Dean could, they fought.
Dean has the First Blade, it's changing him, Sam sees it, Dean can't or likes it and won't admit it, they're going to fight about it.
Abaddon, just like Dick Roman in Season 7, is so quickly dispatched with the Cain Blade that it makes the viewer wonder why the Winchesters ever saw her as a threat in the first place. Seriously, that's how the writers chose to have her killed? I'll admit, the effects were great and her actual death was astounding for broadcast TV, hats off to the CG effects people, it looked better than anything I've previously seen on Supernatural. It's just a shame that such a pivotal character to this season's story arc is defeated in all of 3 seconds. I get that Dean got wind of the trap and flipped the table on Abaddon, but come on, she practically turned and waited with arms wide open for her demise. The writers for this show seriously need to take a class in about everything. It's just awful. We've all seen mere mortals put up a better fight than a supposed Knight of Hell.
I wish when I came here I had positive things to say about the way this show is going, but I don't, so I can't, so instead I rant.
I give this episode 3 stars. Not a complete turd like "Bloodlines", but not that great either. And the Crowley son ploy is another rehash. Seriously, throw out everything that's been done and take us in a new direction. Lazy writing and a rehashed plots begets jaded fans.