I have such mixed reactions to this one.
Of the good:
The Reaper concept altogether.
Bobby was in fact the post-DT goto guy, as many fic authors had predicted.
Sam's refusal to give up on the Impala, which is a symbolic representation of Dean (and he was right about Dean's feelings)
The Ouija board solution (!)
John's REAL plan to save Dean (and the excellent conflicting feelings we have about it, knowing that it will screw the boys up good pretty much forever)
We found out JDM was a lefty...
Of the bad:
Dean wandering around the hospital half-monologuing didn't work very well for me. This wasn't Jensen's best acting, and the lines were a little wooden.
John's lack of an appropriate goodbye to either son.
THE TOTAL LACK OF TOUCHING OF ANY KIND during these traumatic, end-of-life events.
Sorry, but that last one pissed me off bigtime.
It just rang horribly false throughout the episode. I don't care what macho issues the family might have (which I think Kripke has gone overboard on, BTW). But when someone is near death, in a coma, and maybe not coming back... you touch them. You hold their hand, in case "feeling" is the only thing that might break through to them. Because you have to, and it's the only emotional reassurance you're going to get just now. Because you can't help yourself, and there's no-one there to criticize you for doing it.
The brother that raised you and loved you, and has pretty much always put your interests before his own? No way do you not hang right by him and touch him, knowing that he might disappear at any moment and hoping to god that he doesn't.
And you say goodbye to your sons by sending one off on a fool's errand (understandable, but not even a shoulder pat on the way out) and... you don't even hug the other one, knowing that this is it? Not to mention not being a great deal more broken up about the choice you're making and the finality of this particular moment?
Those parts just didn't even seem realistic to me. The seemed like enormous character missteps, and they blunted the emotion of something that should have been overpoweringly painful to watch.
Does Kripke have Wincest paranoia? Is that what's at work here? Because taking this path won't get rid of it, but it sure takes some of the punch and realism out of the characters. :(
Now, John's decision? A double-edged sword, because the boys will blame themselves forever for that one. But he did at last put his sons above his own obsession with vengeance.
And I'll miss him, though I think his choice was the right one.