James’s review published on Letterboxd :
at first you think it's a meta-cinematic exercise — an interesting one, too because it eschews pastiche and instead takes aim at and nails dozens of film noir beats & micro-beats with charm and subtlety and creativity, never too pleased with its cleverness, truly invested in genre, in cin-é-ma — but eventually you begin to understand that the supernatural elements don't belong to film history, that Rivette is attempting a kind of synergy between the genre patterning in film (in this case, specifically film noir) and the raw materials of mythology and that ultimately, he is just as invested in the latter. the film is a way of trying to unleash what is potent or enduring in fantasy (Rivette claims the mythological elements come from Celtic mythology; ok, like most people, I don't know much about that subject, but whatever relevance that specificity has is ancillary to its ancient quality). — scènes de la vie parallèle — scenes from a parallel "life" or existence — this is myth, these glimpses. but there is a double meaning to this intimation: the vie parallèle of genre cinema is myth. this opens the film up enormously. and yet, in the end it's really best as a hermetic masterpiece, a work that requires a certain sympathy and that stands outside of history because of its reliance on a kind of naïveté possible only during the time and place and circumstances of its creation (and its auteur's mentality); Duelle (and Noroît) are examples of an insane ambition, insane to think that films could be what this is, that one could make films in this way (Rivette suffered a breakdown before he could complete the other two proposed films in the series and tellingly, left things unfinished). classical forms, tropes, movements, etc. are always being cannibalized, combined and recombined, mixed together, synthesized, concatenated but never before or since with such abandon and erudition, with such singular intent.
the film's success rests largely on its capacity to maintain simultaneous different levels of credibility, or more directly, in its capacity to bring off its audacious combinations, elements of documentary praxis contra pure invention and performance, an acute and eccentric sense of the contrast between realism and illusion at the heart of narrative film.