This movie is a bit underrated at 5.6 stars at this moment. The acting is very good from top to bottom. As others have noted it's also an entertaining callback to 70s Italian giallo cinema, both in terms of the lurid, convoluted plot and the self-consciously stylized, artistic visual design.
Similar to some of those classic '70s flicks, at the end of the day the plot within a plot, story within a story of this movie doesn't make complete sense. If you examine it with cold-hearted logic logic you'd have to apply some significant contortions to fill the plot holes and get it to all work out. But also at the end of the day I'm not sure this lack of complete internal logic can really be seen as a flaw since it is a pretty traditional, even defining, feature of this kind of movie.
Bottom line, this is an entertaining movie filled with good acting, a beautiful to look at visual style, consistent suspense, and a pervasive sense of mystery.