My guess on why Ruby didn't tell the boys about Lilith earlier? Because it wasn't the original plan, until the writer's strike fucked everything up. (DAMN YOU, AMPTP!) Minus that slight implausibility, I thought the episode worked (as a whole) fairly well. The last shot (of Dean in hell) was ... underwhelming for me, to say the least, but I enjoyed the rest of the episode. (in the sense where "enjoy" is synonymous with "allowed it to break me mercilessly")