Prior to seeing this movie, I didn't understand what was meant by the term 'film noir'. Film noir, I understood, was an enviable quality in a movie, a dark quality, but it was also an ephemeral quality: I knew it when I saw it in a movie, but could not elucidate precisely what it was.
Blood Simple is the bizarre tale of some small-town Texans (the politically incorrect term likely would be white trash) marginally employed in a variety of jobs: private eye, bartender, loan shark, etc. One thing leads to another and eventually all of the major characters meet grisly ends.
In this vein the movie is fairly predictable: it becomes obvious about half way through the movie that the only way for the movie to end is for everyone to die; that is, the movie requires that none of its major characters survive the world in which they inhabit.
So, no, the movie is not to be judged in the way Hitchcock is to be judged; the movie is predictable.
But what of its evocative atmosphere? What of its unstabilizing effect on the viewer? Watching this movie is like having bugs crawl over you: you want it over with as soon as possible so you can escape the bizarre sensations. If the genius of film is that it excites the emotions (hell, even Die Hard does this), then this movie is the apotheosis of emotional excitement.