The NYT says, "Remarkable for a low-budget western, “Lonely Are the Brave” poses uneasy questions about the idea, and value, of heroism." Time Out calls it "A striking modern Western" and closes with this: "Beautifully acted by a superb cast, it's a gripping, elegiac movie, imbued with a very real nostalgia for a vanished world."
DVD Talk concludes:
As high as a recommendation will go. Lonely are the Brave is a true winner. A deep and thoughtful take on the modern western, it's got nail-biting action alongside sharply drawn characters. Kirk Douglas has never been better ... and the tale of one man trying to carry on despite modernity's every effort to knock him off his horse has a lasting significance. ... A bonafide lost classic.
Roger Ebert calls it "Kirk Douglas' unrecognized masterpiece". Rotten Tomatoes has a critics rating of 90%.