Based on previous OGLs, this book will be more of a toolkit, and have very little if any setting. I would be surprised if they had anything other than references, like the previous 3 OGL books.
I think that is the OGL line's greatest strength and weakness. They provide you with every tool you might need, but don't tell you what to do with it. That opens up maximum flexibility to their product. But even a couple of pages of campaign ideas or plot hooks would be welcome in my book - even if they showed up on the Mongoose site. That would be grand and likely all I need to get my mind off and running on stories.
That was a nice thing about OGL horror. It did have a mini campaign setting in the back and some hooks.
In understand the value of what they are doing, though. It makes the book ultimately flexible to anything the GM wants to accomplish.
If I had one knock on this line it would be that, and *ONLY* that.
Cuz other then that the three OGL books out so far have been some of may favorite D20/OGL products.
They are simply top notch.