This is a classic Western, enjoyable both on its own terms and as an important film in the history of the genre. John Wayne isn't good in everything (I know I hold the minority view here), but he's good in this. Small character interactions (some friendly, a few comic, some conflicting) alternate nicely with large scenic views. It's hard to find any fault with this movie.
part 1/13 via youtube:
All the parts, except for one from the middle of the movie, are accessible from this link.
It's on the Images Journal list of 30 Great Westerns and there's a description there. FilmSite.org opens their review with this:
Red River (1948) is a classic and complex western (and considered by many critics to be one of the ten best westerns ever made). It is a sweeping, epic story about a cattle drive (historically based on the opening of the Chisholm Trail in 1867) and a film of rivalry and rebellion, spanning a time period of fifteen years.Wild West Web calls it "memorable". The Book 1001 Movies You Must See Before You Die says,
Hawks, the great film chronicler of macho pursuits, here stages the definitive cow opera, putting all other cattle-drive Westerns in the shade with beautiful, lyrical, exciting sequences of stampeding, rough weather, cowboying, and Indian skirmishes.Roger Ebert considers it a "great film". Rotten Tomatoes gives it a score of 100%.
Other Westerns I've seen are listed here.