On review aggregator Rotten Tomatoes, the film has an approval rating of 88% based on 24 reviews.[5] On Metacritic, the film has a weighted average score of 58 out of 100, based on 9 critics, indicating "Mixed or average reviews".[6]
Sandra Hall from The Sydney Morning Herald gave the film four stars and called it "a hypnotic experience – and an audacious one – given the film’s stately pace and scorn for action, suspense and all the other conventional narrative devices." continuing "But it’s put together with such a finely tuned instinct for the sensuous power of the earth’s splendours that it’s very seductive."[7]
Writing in the Austin Chronicle Richard Whittaker gave 3 1/2 stars concluding "Yes, River flows in the wake of other documentaries, and some have called it redundant. But it is rather another drop in the flood of documentaries, and without all those drops, especially one so beautiful and challenging, there will never be any erosion of our antipathy to change. If the purpose of Mountain was to humble the viewer, then River is intended to quietly terrify us. Maybe that's exactly what we need."[8]
Michael Hogan from The Telegraph gave the film one out of five stars finishing "This wasn’t meditative enough to qualify as “Slow TV”, partly because neither Dafoe nor the musicians would pipe down. By the time the credits rolled on River, I wanted to throw myself into the nearest one."[9]
