I'm surprised that this isn't X-rated. This only gets 3 stars because of the music playing during... THAT scene. It made me laugh way too hard at that part.
Unfortunately, the renderings took away from my enjoyment of the rest of the movie. This feels more like an experiment in film making than a horror movie. This movie needed more practical effects and more monster, and less time spent with the unrelatable characters.
The scene transitions (both timing and method) also felt as if they contributed toward a narrative that works better on paper than on the screen. This might even work a bit better on a stage (ignore the sexual parts...) than on the screen. The screenwriter should be sure to properly adapt to the medium being used to portray the story. This is probably the producers' fault as well when they were assembling the final narrative after shooting.
In short: relate the soundtrack to the action, make the characters relatable, use proper practical effects (see listings in the trivia/goofs/continuity/anachronisms), and write for the screen.