There's no doubt the plot had weaknesses, but I loved the way they managed to show how desperate Sam and Dean were with minimal action. Sam flinching when the door was closed, Dean's dead-eyed look after two weeks had passed...It all felt so visceral to me. These guys don't talk, they don't express their feelings (except when they DO!) and yet I FELT how miserable it was for them to be separated and isolated from each other. That they came to the same conclusion felt real to me. I need to go back and watch this again, but overall I think I really loved it :)