I am not what you would call a massive X-Files geek; I haven't watched all of the television series yet, I haven't watched any of the movies, and I haven't read all of the books. That having been said I have enjoyed the first eight seasons, and some very special episodes.
I purchased The Science of The X-Files, having read Jeanne Cavelos' other outing The Science of Star Wars.
If you enjoy reading about how some of the phenomena in the X-Files Universe might be possible in the light of modern science then this book is for you. If you are a novice/amateur writter like me - looking for ideas, or some science background that comes in a context already formatted to correlate with a fictional world, this is for you. If you live, breath, eat and sleep The X-Files then needless to say this is for you.
Some of the text comes across in an unimaginative and unengaging fashion; where the author attempts to get to her point through a series of seemingly endless bouts of science-stuff illegible to the common simpleton - but these aren't common. In fact, the author often uses examples from everyday like, and her pet iguana, to bring the airy science down to a more understandable level... she doesn't do this all the time, but often enough to bring out the ocassional smile, or even the odd laugh...
I'd definitely recommend.