Not a great Bava film, but a good one. While sometimes crossing from dangerous into ludicrous, the film maintains tension and a sense of peril throughout. A few scenes create the cringing sympathy of later films like "Last House on the Left". I haven't seen the English language cut, but the Italian is impressive for its ability to make you believe that you've witnessed offscreen horrors.
Not a perfect movie, but one that feels important in founding the survival genre of horror.