But for a rather ridiculous ending, this is a pretty solid effort, especially for Season Eight.
There is a good amount of action and the episode flows with a confident ease. The soundtrack is particularly good. The plot is a bit thin but I really like the savage energy put into protecting Scully and her baby by the three lead male actors, as though they are protecting the herd from the jackals and the wolves circling just outside the door. Speaking of which, how is it that Krycek can be alone in the same room with the three men he has tried to kill throughout the series without one of them so much as taking a slap at him? Just wondering...
Now about that ending, what is it that Agent Crane is doing exactly? From the closing shot of his implanted neck, he would appear to be one of "them" (i.e. a Super Soldier) and so we would expect that he would try to stop Scully, which it appears he is doing with the garbage truck pulling out to block the car carying Scully. But then Mulder makes a miraculous tackle of Billy Miles up on the rooftop and Billy plummets into said garbage truck (a spectacularly done stunt, by the way). Crane suddenly motions the garbage truck onward and directs Scully to "go, go, go!" It doesn't make any sense, either Crane was trying to block Scully or he was setting up the garbage truck to catch Billy's fall (which he would have had no way to predict). It's a disappointing ending to what until then has been a solid episode.
One more nag, when Mulder and Scully leave her apartment with Billy on their trail, Mulder rather curtly tells Scully to walk around and get into his car. I know they are pressed for time, but wouldn't you have liked to have seen Mulder at least open the door for his nine-month pregnant partner?