The two big positives of this giallo are: a creepy, abstract Morricone score and lots of wonderfully composed shots featuring various modern/brutalist architecture backdrops. One of these days I need to see that hotel spiral staircase in person (also seen in Dr. Goldfoot and a few other 70s Italian films).
I mostly found the story to be lacking in suspense or even just a basic sense of mystery and intrigue. It think most of this had to do with underdeveloped supporting characters and confusing/bad/unfocused editing. There a scene where a paraplegic woman is stalked by a killer except that they never establish that a killer is actually stalking her. It just becomes woman crawling on the ground for five minutes.