Interesting episode - a little on the cheap side, but plenty of tension and moves at a good pace.
The ending seemed a little convenient - with almost no clues, Mulder uses his behavioural psychology experience to identify the boy in the coma as responsible, when it would have been difficult for any viewing to imagine that.
I have to admit, I was left wondering what had actually happened- if the boy was killing people, why didn't he kill the medical examiner's daughter? Or was he simply offering up his friends to the aliens, who were scared off by the intrusion of Mulder & Scully?
Still, a decent opening episode that clearly establishes essential themes from the beginning. Not least Smoking Man, who I know is going to come into his own later...