I picked up this one solely on the basis of its having John Cassavetes in it. Yes, it is low-budget, but despite that -- or maybe because of it -- the film is surprisingly effective. It's creepy. There's some gore but the slicing & dicing is almost all off-camera. With the exception of one scene about mid-movie, we don't see any of it. That works to make the movie more eerie -- we aren't distracted by the gross-out effect.
Cassavetes shows his talent -- he can make the worst dialogue sound believable. Unfortunately, the side effect of this is to make his coworkers sound even worse than they might have. Because a lot of the dialogue in this movie does stink out loud. On the other hand, there were a number of interesting scenes where you expected someone to break out in positively bad, cliched dialogue and instead -- nothing was said.
Others have commented on the creepiness of the doctor's quasi-incestuous relation with his daughter. It's all true. In fact, it was so blatant I was shocked that it would even get onto the screen. That kind of behavior is something that almost never gets shown.
Summary: good if you want to see a creepy movie with a great actor and lots of strange things going on. Not great art but worth a look.