Delta Green has long been my favourite horror setting, and this rulebook delivers exactly what i am lookign for in DG rules-wise in spades. The sanity system tweaks, the bonds, the simple ways to do modern combat, the elegant skill system that custs down on rolls. Brilliant stuff. This would also work for any modern horror or investigative game.
The book itself is gorgeous and solid, and the PDF is just as nice to look at.
If you want dark modern horror with personal cost you will not regret buying this.