This one is slightly odd tonally - there is a bit of poliziotteschi, some giallo and some broad and slapstick humour. If I had to pick a genre to pigeon-hole it in it would be a poliziotteschi. It owes more to that genre than giallo for me.
Giallo purists will likely be disappointed. Some giallos have a little humour so that isn't necessarily a problem. This has more humour than I've seen in a giallo before but I think the giallo label goes by the wayside for me for a few reasons. The main one - it can't really be a giallo if you see the face of the killer during the first scenes of the film. After seeing the killer it is not a whodunnit, more of a who-hired-them-to-do-it and why? It also leaves you dangling as far as exactly what the main character's role or job is until about 40 minutes in. A few other fairly crucial giallo conventions or tropes are flouted here but I won't say which as they would be potential spoilers.
There are some heavy nods to (or maybe little borrowings from) Profondo Rosso, which precedes this by only a few months - evidence of how quickly these films were made. The first track on the soundtrack is certainly Goblin-esque and the trashy, falling-apart car I assume was "inspired" by Argento's film.
The tone wobbles around and this may make or break the film for you. It feels deliberate and mischievous rather than clumsy. Once you get that it will break with convention, and play with tone and genre I think it is a lot of fun. The price you pay is less tension, although some is achieved especially in the latter half. It is reasonably paced and a few bits of the humour work. The main two characters interact quite nicely together. There is no glaring deadwood in terms of the actors. The last hour of the film is more conventional and rattles along well.
Glasses (spectacles) are a running theme - the main character spends the whole film repeatedly breaking his prescription glasses and the killer wears mirrored sunglasses (which enable a few nice little camera shots).
I can't resist mentioning two other things. (I guess this technically counts as a spoiler but it is not related to any plot or anything crucial). Firstly, during a car chase they hit the front of a bicycle and when the bicycle loses its front wheel it magically turns into a unicycle leading to a wobbly ride and fall. Secondly, again in a car chase, there is an unfortunate pedestrian who is narrowly missed (twice) and manages to contort himself into an almost-breakdance-move headspin both times before dizzyingly walking into a lamppost to knock himself out. (Was this breakdancing move around in 1975? - I don't know).
The subject matter should be dark. Abuse/prostitution of underage girls (a la What Have You Done To Solange and What Have They Done To Your Daughters), a network of corruption, cover-ups, murder etc.....). This film feels less dark, depressing and gritty and has less exploitation-type sequences. In fact, for this type of film it is quite light on nudity. If that disappoints you it does have a topless Barbara Magnolfi in what seems to be her first credited role - if you are a fan of 70s Italian genre films you will possibly know her from Suspiria (as Olga) and Sister of Ursula (in the lead role).
With the subject matter it seems wrong to say but this film is quite fun. Have a look.
I definitely like it. Just don't come in to it with a fixed idea of what genre it is and what that genre should constrain it to.
