As some of the other reviews have already stated, the print of the movie that is available is very poor. So it is not quite clear whether Melville wanted to have the washed-out look of the picture or whether it is just plain bad quality. Even rare TV screenings do not offer an improved version (ARTE).
The relationship between the young ex-paratrooper/boxer/secretary (Belmondo) and the old bank owner/colonial adventurer (Vanel) is quite interesting and also stands for the generational conflict of the 1960s. Obviously, some of the plot is somewhat stretched but the tension between the main characters is excellently played out. Melville wanted Spencer Tracy for the Vanel part, but Tracy's health situation made any form of outdoor filming (not to mention insurance for this) Impossible. Belmondo, who is fooling around in Godard's "Breathless" and posing as a Bogart style tough guy, really plays a film noir character in this one. The way he treats his girlfriend at the beginning of the movie makes his protagonist almost unlikeable. In the damp Louisiana setting at the end of the movie, the whole affair really turns into a veritable noir.