This movie is a ripoff of James Cain's novel, THE POSTMAN ALWAYS RINGS TWICE. Apparently, the director and producer never bothered to pay for rights to this story--perhaps the fact that we were in the middle of fighting the Italians in WWII might account for their forgetting to consider royalties! Despite this, the movie isn't really just an Italian version of the Hollywood movie. In some ways it's a lot better and in other ways, it is definitely not.
The three central characters in this movie are really pretty ugly people. In fact, the male and female lovers are a bit icky-looking. The male lead is pretty ordinary except for his profuse body hair (particularly on the back and shoulders) and his lady love is, to put it frankly, unattractive. They are a very, very far cry from Lana Turner and John Garfield in the Hollywood version. And the ill-fated husband is really, really obese and loves to walk around shirtless--and his counterpart in the American film, Cecil Kellaway is definitely better looking (and probably better looking than the other two Italian leads, actually). And this unattractiveness is generally a reason I actually preferred the Italian film--since I just could NOT imagine a finely coiffed "dish" like Lana Turner in the middle of nowhere married to Kellaway--I am 100% sure she would have had dozens of better offers! Whereas, the Italian wife frankly might NOT have been able to do much better and this made the marriage actually believable.
Part of the Italian film's believability comes from the blunt way it handles sex. The sanitized American film tries to make you believe that although Turner and Garfield kill Kellaway, they never actually get around to sex! This is pretty silly and totally unrealistic. In addition to the casual sexuality of the film, it's also pretty casual in showing the seamy side of life--with lots of sweaty people, a fly strip hanging over the kitchen table and everyone appeared to need a bath.
The movie is also pretty fast-paced compared to the over-long American film. And what you get due to brevity isn't all good. The film lacks a lot of the style and polish of the American film--with grainier footage, relatively poor orchestration and sets. It sure ain't a pretty film, but the Neo-Realistic-like style makes the film seem more realistic. But it cannot make up for the short-cuts in the plot. Many of the plot elements in the later American version are either missing entirely or glossed over. And the ending seems a lot less interesting than the American film--and misses the entire human nature dilemma when Turner and Garfield turn on each other like rats (the best part of the American film).
So which is the better film? Well, a lot of this probably depends on you. As for me, the Warner Brothers film was simply too polished and too unrealistic (though many like this style and may dislike watching films with subtitles)--but it packed a great ending. And the Italian film was much, much more realistic--until the crappy ending that seemed too rushed. So neither film is exactly great, but I'd give my nod to the Italian one being a bit better. It's too bad they couldn't have combined the best elements of both films into one exceptional film.

When a small glob of space age silly putty lands on earth it soon begins consuming earthlings and putting on weight. The only part of this senseless drivel that I enjoyed was all the cool classic cars. This dog had so many holes it could be sliced and sold for swiss cheese. This thing actually made 20 million bucks? And McQueen's salary was 3K? All were vastly overpaid. The 'monster' looked a lot like a large beanbag and the 'teens' looked as though they could have children approaching their teen-age years. And those blasts from the shotgun; sounded like a pellet rifle with a sound suppressor. The ending was pitifully trite; obviously the producers were leaving the door open for a sequel....and there were many. Thumbs down.