This is among the crispest written rule books I've ever read. Frankly, they explain the Call of Cthulhu rules much better than the Cthulhu rule book does itself. On top of that, you've got the wonderful backdrop of the Laundry novels as a setting. Anyone who would like a small dash of black humor in their modern day Mythos game would LOVE this game.
If you play Call of Cthulhu . . . get this game.
If you enjoy the Charles Stross novels . . . get this game.
If you want to play a modern supernatural game that feels like James Bond meets The Office meets Cthulhu . . . get this game.
It's on sale for $11 PDF right now?! Incredible deal for this great game/sourcebook.