Good things first: This is a Scully centered episode which in itself is already a garant for a +5 rating because of GA's acting.
Sadly the episode doesn't offer much more than a couple of opportunities for GA to show what an amazing actress she is. The first twenty minutes of this episode are tedious at best. The suspense of wether we get to see Mulder again is actually non-existent (need not even read the news - just read the credits) and therefor painful in it's perseverance.
Then the show takes a turn with again more plotholes than I would have thought a single writer could come up with. Not going to bore you with the details because then it would be really painful to watch. The soundtrack is good though and the actors really give it their best shot.
Also you shouldn't miss this because of the information that is revealed at the end.