Just got out of this. A fun popcorn movie that could have been tightened up a bit more, but still an overall good time with some very funny yet gruesome deaths. It sort of feels like Perkins was creating his own take of a Blumhouse film, but with a bit more gore. But if you're squeamish, most of the gore is pretty campy, which is really it's salvation IMO. The "Respiratory Stimulant" and movie poster were both great giveaways, felt a bit William Castle. And Osgood Perkins was there in person to introduce the film!
Also, Vidiots just posted a small clip of Demi Moore speaking about some of the messages in The Substance