Wow, it's really bad.  Shockingly bad.  Absolutely chock-full of filmmaking and camera based errors, which is surprising coming from the guy who wrote the amazing film, <i>The Ritual</i>.  But the prose is awful, the characters are awful, and most of the book is just a relentless infodump.  In the final act, it picks up a bit, but it's way too little, way too late.  

And the ending is pretty stupid.