I haven't read the book, though I have seen the original tv adaptation which was excellent. I wasn't having a go at the 12A cert as such, I just thought it would make a terrific '15' type horror.
Insidious was a great example of that. I'm certainly going to see it. Maybe I just yearn for the old Hammer 'X' certificate days
To be honest, I have no interest in total CGI horror. As an example,
The Innocents is one of the scariest films I've ever seen.