“From Beyond” is hypothetically based on the Lovecraft short story of the same name, and it does retain the basic concept- a mad scientist invents a machine that stimulates the pineal gland and all hell breaks loose. Almost everything in the first few minutes can be related to the story- almost everything after that cannot.
Two things you'll never find in a Lovecraft story are sex and gore. You won't even find any women in a Lovecraft story except the occasional evil witch- the guy was just creepy that way. If you made a movie without any women in it these days, it would seem quite strange, but this movie takes it a good deal more than one step in the other direction and throws in a fair bit of kinky sex. If Lovecraft himself actually saw the movie, he would probably faint.
Then there's the brain eating thing. Eating brains is certainly horrific, but not in a Lovecraftian way. So when everyone in the movie starts having kinky sex and eating each other's brains, it parts company completely with Lovecraft. If you're interested in a pretty-good-by-Eighties-standards shock horror movie, this one is pretty fun. If you're hoping to see a Lovecraftian horror movie- you'll have to keep waiting.