I'm not a fan of movie horror--my imagination provides plenty of detail, thanks--so I wasn't familiar with the "final girls" trope. It might have made an interesting basis for a novel, though, if only.
If only Sager hadn't felt compelled to yammer on through pages of trivial and ineffective dialog and description. If only there had not been yet another unreliable, unlikeable main character, along with plenty of sex, booze, drugs, and overall stupid behavior. If only the plot hadn't been so predictable. I had a pretty solid hunch fairly early about who the killer was, although to be fair some of the twists en route to the end were unexpected, if somewhat contrived.
After about 100 pages, I ended up skimming through to the end. Despite all the hype and blurbs from well-known authors, I think this one was a waste of my time.