There is always an interesting tension between movies and their source material. A fairly common pattern is for the movie to be initially compared (often unfavorably) to the novel, but, as time goes on, to develop an independent identity. It looks to me as though Sam Peckinpah's The Getaway is benefiting from this process.
However, Jim Thompson aficionados have some issues. Primarily, there's the novel's ending, which, in the movie, isn't there. No spoilers here, except to say that Thompson takes his story to a ghastly denouement that borders on the surreal and Peckinpah does not. The book's ending may have been unfilmable in any convincing way (Thompson's The Killer Inside Me has a similar problem), in which case Peckinpah made the right move, leaving us with a first-rate heist movie.
But if we want more of a Thompson feel, we're back to a Lana-Turner-type problem. This is a matter of framing. If we call Garnett's Postman melodrama-noir, Turner is just right. If we call Getaway a heist movie, Steve McQueen is just right, and we can watch two sharp movies and go on our way.
But if we return to the source, it's clear McQueen is not on the same track as Thompson. Even when McQueen plays a bad-ass, which he generally does, he's a bad-ass with a code, a tough guy in the heroic mode. Thompson's protagonists, generally speaking, aren't just bad-ass, they're psychotic; and if they follow a code at all, it's so twisted you could spend the rest of your life trying to decipher it. Heroism is not part of the Jim Thompson repertoire of characteristics. While McQueen's persona is up front - what you see is what he is - the false front is what Thompson's boys are all about. To watch that played out on film, catch Philippe Noiret's performance in Coup de torchon (Bertrand Tavernier - 1981) based on Thompson's 1964 novel, Pop.1280.
Still, The Postman Always Rings Twice ('46) and The Getaway ('72), have a lot going for them. I like them the way they are.
But if someone does figure how to shoot Thompson's ending, I'll certainly be interested.