I bought this last week - it's really well done and very original. In addition to the monster stats, there is *a lot* of really good fluff. It's published under the OGL but does not use the d20 logo, and for good reason: it's definitely mature readers only.
The b/w artwork inside is amazing. In fact, the artist (Dave Allsop) is also one of the authors, and the creature concepts are mostly his. Adrian Bott is the co-author and handled the stats too. As far as I can tell, the stats are pretty solid, but I'm no John Cooper.
The monsters are very unique and original, mostly undead, outsiders and fey. What I really liked is that every monster has a detailed description (in a section called "All That Remains") of what you'd find in an autopy and the crime scene of one of the victims. There's a lot of great fluff like framing fiction, transcripts of police interrogations, diary entries, that sort of thing - it's a great read.
The back of the book says "Modern Horrors for the 3.5 Edition Game", but the book mostly uses the d20 Modern rules. At least one monster had the D&D description for regeneration with nonlethal damage that does hit point damage (dementia larvae), but you can easily replace that with the entry for regeneration in the d20 Modern core rulebook (found in the monster description for trolls). Also, there are no allegiances (or alignments for that matter) given. I did like the inclusion of Horror save DCs for the OGL Horror game from Mongoose Publishing (also found in Modern: Occult Horrors PDF from Ronin Arts).
There's also an adventure in the back of the book (again, the NPCs use d20 Modern stats).
These are all new, very original monsters and a nice shot in the arm for any modern horror campaign where the usual suspects are becoming a bit stale. I think anyone who picks this up will find it to be a great resource.