How bad is it? It's cheap and tremendously overacted.
Should you see it? Definitely. It's the first great terrible film.
When I first read about this movie, I thought it would be horrifying. For example, a man plucks out a cat's eye and then eats it. It's so poorly done, however, that it's fun, rather than scary.
The story has a mad scientist trying to bring life to the dead. His assistant is an actor who dresses up as the coroner so the two of them can work on a body in the morgue. While they do this, two men (janitors?) watch and have one of the most entertainingly stupid conversations ever committed to film. Later, the doctor causes a disembodied heart to beat and then tells his assistant that he (the doctor) is going to kill him (the actor) and bring him back. The actor then kills the doctor instead. Thinking that the doctor will be missed, but he won't, he decides to dress up as the doctor and take over his practice - including the experiments. We get to see a man who believes he's a gorilla (a la Murders in the Rue Morgue), then the cat's eye thing - a real one-eyed cat was used, and we get to see some brief nudity. Then we get to see the actor's wife and three other women in lingerie behaving in what Esper and wife must've thought was a provocative way; the brunette with the Betty Boop voice makes me laugh whenever she speaks, one prances around the room and another uses one of those old-timey shake-your-weight-off-with-a-vibrating-belt devices. Meanwhile, two women have a cat-fight with syringes in the basement! Lastly, the police arrive to discover that a man has been entombed in a wall with a live cat (also from Poe. "Cask of Amontillado?"). The cop, leading the actor away, has the final word: "Man, you're crazy!"
Esper made a number of terrible films, the ones after the Hays Code skirting decency standards by pretending to be educational and by not being shown in movie theaters. "How to Undress for Your Husband" does not live up to its title, unfortunately, but all his films have something entertaining; "Cocaine Fiends" has a scene where a prop window slams shut by itself and startles the cast, but they didn't retake the shot. "Maniac" remains the one essential Esper film.