How bad is it? Pretty bad, even by 1980's slasher standards.
Should you see it? No.
There are a few people who swear this is a misunderstood gem; I am not one of them. A bunch of unappealing characters in a low-rent apartment building get killed in a mysterious way, perhaps by a dog. Mitch Pileggi (best known from "The X-Files") has his first role and Aldo Ray plays the owner of the place. There's a prank where a dead dog is put in a bed and then another one that goes wrong and electrocutes a guy; it's after this that the horror starts and the characters stop. It's slow. The surprise payoff is not a surprise - and you really won't care by that time - and the most interesting thing in the film turns out to be a Deep Throat pinball machine (I saw one in real life about the time this came out).