Why the hell would he kill off Jon Snow after building him up so much? He was made out to be the central focus of the storyline, just like Tyrion and Kalisi are. Makes no sense to kill him off, especially in such a stupid way. Snow is smarter than that, he should have sensed that it was a trap.
My wife's theory is that the red witch is going to save him, that's why she's at Castle Black again. We've thought for a while that Snow is royalty, and the rightful heir. Maybe her visions were of Snow not Stannis.
Damn this show for fucking with my emotions.