I think this is the first time I've ever given a 5/5 rating to any product, because I tend to be very picky, and often end up thinking "I could have done a better job than this!"
Not this time. No way. I kept thinking to myself "If I only I could write supplements like this"!
Simply put, Delta Green is amazing. I don't think I'll actually ever run a Modern Spies vs Mythos campaign (its not the sort of thing my players go for) but that is beside the point. This book is so full of cults, organizations, historical time lines and detailed character write-ups that I will be stealing ideas from this book for years to come, to adapt to my various campaigns.
I really can't praise this book highly enough.
[5 of 5 Stars!]