Unknown Armies is probably the single most brilliant game I've read and played. For those unaware, its somewhat loosely classified as the modern transcendental horror. It screams for you to incorporate weird events from our history into the secret history of the world. Did Kitty Genovese ascend as the avatar of the Victim? Did Anthony di Stasio become the first entropomancer when he surfed the 15 foot wave of boiling molasses in 1919? At least in my campaign, yes.
The books are fantastically written, and the published scenarios among the best I've run. Much like the "Planescape Twist", theres a definate vibe you can feel with the setting. Movies like Intacto, Paranoia 1.0, the Lost Room and books like House of Leaves fit into this category, of a hidden wierdness lurking just under a mundane seeming world. What I preferred is that its much more humancentric than WoD.