The plot is straightforward and the milieu is entirely familiar-- open range vs. fenced farming, reformed gunslinger vs. trigger-happy kid, lots of grizzled guys and leather vests, a pointless saloon girl-- but it has enough originality and a solid enough script to transcend formula. It also has two crucial bonuses:
First, the location. There's only one long shot showing the entire Western town, but I've never seen a more decrepit or believable one- - because it's a real one. Rosita, Colorado, west of Pueblo, was well on its way to becoming a ghost town in the late 1950s (it actually is one now, in the middle of exurbs). It had only three or four wooden buildings, plus a few scattered homesteads between them and the mountains. It delivers total verisimilitude. Quite a few scenes are shot in the wilderness, too, with meadows bursting with purple wildflowers. A real Western settlement in a gorgeous wilderness-- it is iconic, far more than John Ford's Monument Valley, which is unrepresentative of any other Western landscape.
Second, the supporting cast. The faces are all more familiar than the names. Royal Dano and Irene Tedrow as squatters, Charles McGraw, Ray Teal (Bonanza's sheriff), Douglas Spencer, and as barkeeps, the wonderful Stanley Adams (Cyrano Jones, tribble salesman) and the forever-unheralded Jay Adler (Stella's brother). Adler's worth his weight in silver-- Rosita was a silver-mining settlement-- and he's in the first scene so catch that at least.
The reason that mother lode of character actors matters is because-- along with always-fine Donald Crisp and better-with-age Robert Taylor-- they carry this movie. The relative novices involved-- writer Rod Serling, actress/singer Julie London, and fish-out-of-water John Cassevetes -- handle their duties well enough. But they just can't measure up to that roster of seasoned pros, a cast that has been in so many Westerns, they feel as authentic as Rosita.