How bad is it? It wasn't released, it escaped after sleeping for 30 years.
Should you see it? Yes. I can just barely recommend seeing this mess.
By the way, there's no way that bed fits through the doors. And the stones of the exterior don't match the brick of the interior. The film's so slow you have to look for things to watch. There is occasional nudity to perk things up.
Three women are in the final group of victims, who take up most of the screen time, along with the brother of one of them, who's looking for her. The brother drives over a bag with her clothes, for no apparent reason. The black woman half-escapes, her legs being digested and the girl not yet eaten apparently goes mad, which explains (maybe) why she doesn't try to flee or to warn her brother when he comes. He gets his hands eaten and treats it like a science experiment.
The demon that created the evil bed slumbers in a tree once every ten years and this just happens to be that night (are you still with me?), so the guy in the drawing can tell the crazy girl (played by the presumably pseudonymous Rosa Luxemburg) how to stop the bed. "But I lied," he explains, and she's to be sacrificed, too, to resurrect a girl buried outside (really, are you still there?) and free the guy in the drawing.
The bed burns, outside, for a few minutes.