Carson Lund’s review published on Letterboxd :
Shock's premise alone is peak psychosexual nastiness: while a woman (Daria Nicolodi), still reeling from her previous husband’s heroine-influenced suicide, attempts to adjust to living in her familiar home with her new partner, the spirit of her past lover takes control of their frizzy-haired young son to seek revenge (for what exactly, we don't know) and maybe a little titillation from his old wife along the way. Bava begins with the exaggerated image of a perfect nuclear family—complete with histrionic smiles, regiments for playtime and bedtime, and sunny acoustic guitar jangles—only to methodically introduce the seedy undercurrents of a repressed past, one still fully latent in the house itself. An oversized and animate ceramic hand sculpture, a grand piano booby-trapped with razor blades, and a newly installed tree swing with powers of its own are some of the household dressings that terrorize the twitchy matriarch, and Bava’s staccato intercutting ties these instances to the possessed bodily tremors of the boy-medium. (Young actor David Colin Jr.’s nimble shifts between cheery obnoxiousness and freaky stillness sell the paranormal linkages as well as any of the editing tricks, though his facility with the former emotional range evidently short-circuited his career.)
Shock coasts on such haunted-house foreplay for about as long as Bava can sustain it before collapsing majestically into a molasses flow of nightmarish imagery: a trippy POV sequence shot with filters that stretch the image like taffy; a long close-up of Nicolodi staring her demon in the face, midnight wind blowing her hair this way and that in slow-motion; and, most scarring of all, a rat climbing up her blouse to violate her, a shot that brings the inherent sleaziness of the premise to a startling apex. Macabre fixings aside, Bava’s final freakout is sincerely concerned with the implications of remarriage, with the nature of starting a family anew, and with the collective repression and performance of domestic harmony that ensues. The final image—of the new generation bonding tragically with the old in a play-acted teatime—could hardly be more carefully judged.