One of the coolest Westerns I've ever seen. It angered John Wayne so much that he wrote Clint Eastwood (its actor and director) to complain about the film. The above writeups do not convey the stylistic mashup and brilliance of Eastwood's work.
This film is a cross between A Fistful of Dollars and The Crow, also stylistically lying somewhere between Twilight Zone episode, slasher film and spaghetti Western. The soundtrack for the most part is horror style atmospheric music and ambient sound, and the exposition by flashback is a classic fright film leitmotif.
Not to spoiler the film too much, but the town the Stranger rides into has piled evil on top of evil, moral failure after moral failure, and the result is a dead man. What relation the Stranger has to the dead man is deliberately ambiguous. Avenging angel? Revenant? Relative? The ringleader cries out "WHO ARE YOU?" to the shape of the Stranger, backlit by flames, but receives no answer, and neither do we.
The heavy handed touches in the film, such as the painting of the town red and its renaming to "Hell" ("especially the Church", growls the Stranger), the Twilight Zone swerve at the end and the notion of nemesis repaying evil puts this film on the same footing as what it is - a remake of a 15th Century morality play.
Every sin is punished by a complementary one - murder repaid by murder, and greed repaid with theft and loss of the property the townspeople held so dear. Lust is repaid with rape, and adultery is repaid with the destruction of the marriage that was betrayed.
Eastwood coming out of the flames like a tormenting devil, or silhouetted as a dark shadow against the backdrop of the town. The eerie, haunting choral ambiance and the sound of a whip cutting a man to death. A town bathed in its own symbolic blood with no guilty party unpunished.
The character of the supernatural Western avenger has become iconic. Eastwood's anti-hero has been reused, retold and rehashed in characters such as the Saint of Killers in Preacher, or even as the returning Eric Draven in The Crow.
A horror film? A Western? Both? Neither? Whatever it is, it's atmospheric and riveting, and a movie you either love or hate.