The Italian giallo eventually suffered a lingering, painful death, merging with the inferior American slasher movies in the 1980's and the vastly inferior American "erotic thrillers" in the 1990's (with which today it is virtually indistinguishable). It was clear though that the rot had set in as early as the late 70's with films like "Play Motel" or this one where the sex and nudity that had always been used to season the genre seemed to become its very reason for being. The only thing that separates a film like this from crappy American softcore porn is its almost cheerful political incorrectness, appalling lapses of taste, and a general paucity of silicone breast implants.
Two sisters with a disturbed past check into a seaside hotel where the guests are suddenly being offed by a killer wielding a most unusual murder weapon, a giant dildo! (Amazingly, this was the second Italian film of 1978, after "Red Rings of Fear", to feature the "death-by-dildo" device). I won't spoil the ending by giving away the identity of the killer, but it pretty much spoils itself within the first ten minutes. This one fails utterly as a giallo (or a real movie for that matter), but I guess it kind of succeeds on the level of softcore pornography--the photography is good, the scenery is pretty, and the score is decent. The actresses are also all pretty attractive, especially the one who plays the lounge singer "Stella Shining" (although I don't know that most guys would want to bury their entire face in her backside like one Italian lothario very graphically does here).
I'd recommend this perhaps for giallo completists (and maybe serious porn addicts), but for everyone else. . .uh, probably not.