Neurosis would be at the opposite end of the spectrum from, say, Brilliantine. Imagine songs that average around eight minutes, extreme loudness, relentlessly heavy, monstrous, thundering rhythms. Dirgy sonic assaults that warn of the impending doom. Kind of like slamming your head into a concrete wall until it's disintegrated.
At times it sounds like Satan himself is screaming lyrics like, "Desire's path is low, bleed my eye, heal my stone/I will open a door and bleed your dreams, silently praying for enclosure within the flame of origin" (from "Enclosure in Flame). You can definitely see the influence Neurosis has had on a lot of hardcore/straight-edge bands around the world. Interesting, but hard to sit through for over an hour and through nine songs _ Muzak to drive up the suicide rate.