I made an account just to write a review of this movie because I feel a calling to warn the hapless masses about this movie and to urge everybody reading this to do quite literally anything else with your time other than watch it.
This movie plays out like a below-average Black Mirror episode that has been stretched out and stuffed with grotesque violence and disturbing imagery.
The first 20 minutes or so are intriguing but beyond that there is almost nothing of "substance" in this movie. There is almost no dialogue, no character development, basically no plot. The messages this movie attempts to convey are delivered with the subtlety of category five hurricane. There is absolutely nothing thought-provoking about this movie either. Furthermore, the small budget really shows because this movie has no world building, a maximum of three actual characters, and could have all been filmed in front of a green-screen and you wouldn't be able to tell the difference.
All of this is without even mentioning that this is the most visually disturbing movie I have ever seen in my life. Oh and the ending? forget it- no pay-off whatsoever. Lazy writing, lazy story telling, lazy plot. Only redeeming qualities are the initial concept and some of the cinematography, but even that is overdone and gets irritating quickly. Lastly, the nudity in the movie is completely unnecessary and overdone and goes with all my points above (see: lazy / abject lack of subtlety).
While the concept of "the substance" itself could have been interesting, the way it was executed in this movie was a complete swing and a miss. This is basically just a 2+ hour compilation of nightmare fuel and soft-core porn. Do anything, I repeat, anything else with your time other than watch this movie.