With aggressive stylization, bright colors and quirk, this seemed like a sure winner. Unfortunately, the story never quite broke away from cheap formula.
It is based upon a pretty mundane plot, a whodunnit that not even Ava cares all that much about solving. The grind house aesthetics leave the impression that nobody was taking it all that seriously, and so this seems to have become a self-fulfilling prophecy.
It wasn’t serious enough for drama, nor funny enough for comedy, and so what is it exactly? Those infants who haven’t seen The Exorcist should rent that first in order to see how a serious film deals with this possession phenomenon. There are several more recent ones too. Ava references Exorcist a couple of times but comes nowhere near it.
The closest reference I have here is All Cheerleaders Die, which was a bit more consequential. Just a tiny bit. At least they maintained a sense of actual danger and a theme. Not so here.
Gilding the Allegory (Free)