Aside from the notoriety, and aside from the viciousness (the film leaves you most of all with a taste of viciousness in your mouth, a sour, bitter, metallic taste, akin to that feeling you get reading "The Tin Drum", the piece of metal stuck in the back of your throat), what you get from "Straw Dogs" is a manifestation of personal demons (specifically, Sam Peckinpah's personal demons, but also, both more generally and more acutely, masculine demons) and an exploration of a certain type of male sexuality.
To do the film justice, you need to plug your brain in. Which, on the surface, may not appear to be the case, because the story - what it is - is relatively simple. It's an English western.
David, a mathematician (Dustin Hoffman), is on sabbatical from the university where he teaches. He has left the states and returned with his wife Amy, (Susan George) to the tiny English village in which she grew up. From the word go, David has to contend with the fact that Amy has a history in the town. He also has to contend with the fact that she is younger than him, and bored. Her boredom serves as a distraction from the reason behind his sabbatical. Amy on the other hand has to live with a quiet, "odd" American who does not give her the attention she requires.
Within the town, there are various echoes at work: there is a character called Niles, played by David Warner, who has a known history of problems relating with women (to the extent that he has served time for undisclosed offences); there are the locals, who divide their time between procrastinating over work on David and Amy's roof, and leering at Amy (who periodically informs David about the effect she has on them, how they "lick her all over with their eyes"); and there is David himself, spending a little more time than he really should looking at teenager Sally Thomsett.
All of which feeds into the terrible rape scene (a scene of which Peckinpah is quoted as saying - in the excellent biography "If it moves . . . kill 'em" - "I wanted to film the best rape scene ever" - a line ripe with complexity and moral disorder): Amy is raped by Charlie, leader of the leering locals, who may or may not be her childhood sweetheart (two earlier scenes indicate that (a) something went on years earlier and (b) Charlie took it further then than Amy was happy with).
At some point during the awful protracted rape, for whatever reason (and there is something manifest at work in her face, palpably desire but desire for what - who knows?) she stops fighting and starts (ugly this, but true - this is what happens in the film:) - starts to participate. The participation is taken (by some) to be a playing out of a certain retrogressive masculine attitude (that all women - deep down etc etc etc). However you interpret it - and it does require interpretation, importantly - the participation is at the dark heart of "Straw Dogs"' notoriety. The fact that this is followed by the appearance of a second man, and a second rape, only compounds the difficulty - the cloudiness - that will inevitably surround any attempt to precisely articulate what is going on here.
At which point, the echoes become still more manifest: you have Niles, despised because of his weakness for young girls (and as such - in the context of the character's lives - a "bad" man), you have the men who rape Amy (a fact that remains undisclosed within the body of the film), men who later attempt to avenge themselves on Niles (in a vivid reworking of "Of Mice and Men"), and you have David - a man in whom, perhaps, all of these violent urges conflict.
The film culminates in a series of extremely violent (and ridiculous) altercations, veering wildly between extremes (shotguns firing off left, right and centre, characters riding tricycles and playing bagpipe records, mantraps, boiling fat, fire, pokers, broken glass, wire). But the central relationship - the whole dynamic of the film - between David and Amy continues to fight definition, remaining ultimately unresolved and unclear.
In the end, aside of everything else (aside of the fact that this film lingers with you, you do not watch "Straw Dogs" and leave it at that, those "Straw Dogs" take up residence with you, for a while), you have the fact that this film would not get made today - the Dustin Hoffman character is too complex and too unsympathetic, and there are too many (coldly intellectual) questions raised by what goes on.
It is dissatisfying but intentionally so: this is Peckinpah's "Salo": it demonstrates that resolution is the most ugly abstraction, that what gets wrapped up leaves the viewer with no space for thought: that which is left open, is that which remains discussed. At the end, almost a week after last watching the film, I am reminded of what Ian McEwan wrote in his novel "Black Dogs": "...I came face to face with evil. I didn't quite know it at the time, but I sensed it in my fear - these animals were the creations of debased imaginations, of perverted spirits no amount of social theory could account for. And . . .when conditions are right . . . a terrible cruelty, a viciousness against life erupts, and everyone is surprised by the depth of hatred within . . . (But) This is what I know: Human nature, the human heart, the spirit, the soul, the consciousness itself - call it what you like - in the end, it's all we've got to work with. It has to develop and expand, or the sum of our misery will never diminish."
That is - at last - "Straw Dogs"' role: to develop, to expand, to show us what can be, what needn't be, but what is, and hope that something else (not necessarily finer) but something else, prevails.