Considerably less than the sum of its parts. The English-language title is extremely misleading (the original translates as 'The Vampire's Lover'), for there are plenty of dancers but not much ballet; one of the film's highlights being a supposed 'rehearsal' with the girls cavorting athletically in matching leotards and fishnets as one reclines languidly in the foreground drawing on a cigarette, which resembles a beatnik cabaret act rather than ballet.
Characters aimlessly wander in and out of the plot as well as about the local countryside and the local abandoned castle as in an episode of 'Scooby Doo'. Angelo Baistrocchi's photogaphy - particularly the nighttime exteriors - are pleasing to the eye but far too overlit for the purposes of suspense; while Aldo Piga's score varies wildly in style and suitability from scene to scene. Helene Remy as Luisa and Tina Gloriani as Francesca are both immaculate in their high heels and fifties dresses and hairstyles; maybe too immaculate, since their blonde good looks and their clothes render them so similar it gets difficult in the later stages of the film to keep track who's doing what and to whom at critical moments.
Someone involved in the production was obviously familiar with 'Nosferatu' and 'Vampyr', since a number of images (the wolves emerging from the woods, the coach driver, even the closing shot) have been lifted from the former, and the subjectively shot funeral from the latter.