Being someone who was ecstatic with the new direction Philip Glass took with "Naqoyqatsi", I was eagerly anticipating the release of "The Fog of War". I was not disappointed with it, but I wasn't exactly satisfied either.
Of course, the main difference between this album and Glass's other works is the lack of form. The music doesn't flow as well; doesn't create a mood like some of Glass's other soundtracks. Each track runs about two minutes long; some as short as 43 seconds. With "The Hours" this wasn't a problem, but here most of the tracks sound noticeably different from the one before it.
"The Fog of War" breaks no new ground for Glass, it sounds similar to much of his older work. (Track 28, Unilateralism, is the first movement of the orchestral version of "Company.")
I think it's safe to say that this album most closely resembles "The Thin Blue Line", Glass's soundtrack for Errol Morris's excellent 1988 documentary. Again, the orchestral focus is on strings and brass, with bits of percussion thrown in here and there.
For what it's worth, this album is typical Glass (and there certainly isn't anything wrong with that), moody music that creates a scene, a picture in the listener's mind, but isn't profound or moving like "Koyaanisqatsi" or even the "Etudes", for instance.
"The Fog of War" is one for your collection, but not a necessity for people just starting a Philip Glass library.