Paul Elliott’s review published on Letterboxd:
Lucio Fulci assigns an agitated manner to his direction in bringing this tale of Carol Hammond, a daughter of a British politician implicated in the murder of a decadent neighbour which she perceived in a nightmare.
The screenplay co-written by Fulci ensures that it reaches many of the primary requisites of giallo, especially the excessive violence and salacious fantasy scenarios, which he places first and foremost on the schedule ahead of narrative logic. His employment of filling the screen with fluctuating POV shots and surrealist sequences together with making the most of reflective veneers helped to position him as one of the first filmmakers to capitalise on the trend of the genre, just as they caught financial traction at the Italian box office.
Fulci continually allows the cinematography of Luigi Kuveiller space to undertake a few experimental aspects, and there's a good general use of external locations, including a terrific chase sequence where Carol is chased through Alexander Palace by an aggressor. Unfortunately, Fulci allows his personal feelings to interfere with the portrayal of some of his characters, which function as two-dimensional caricatures, and his disapproving view of counter-culture, inflated as a means of amusement, invariably exasperates after a while.
The feverish editing by Giorgio Serrallonga adds a considerable amount to the underlying aspect of the perceived respectabilities of the middle classes colliding with the counter culture of the period chiming through the majority of the narrative, as does the score by Ennio Morricone which is mostly slanted towards free jazz flavours while still incorporating his more common reflective characteristics.