It lacks a lot of things - decent dialogue for one, but it's an iconic movie with three powerful actors.
I still have "BLONDIE!" echoing in my ears after all these years.
As a period piece, it also does a great job capturing the civil war. Aside from clint’s and Turco’s guns, which were converted 1861 percussions, (not authentic for the time), the cannons, weaponry and costumes were highly authentic and well done.
For me there are two scenes indelibly sketched in my memory of this film. First, the gang start off with a murderous intention as they find out where their quarry is. The ugliness of one of the faces stands out.
Next, the scene in the cemetery. The haunting sound again and again, as Elie Wallach acts as the half crazed seeker of buried gold . The shots of the gravestones in a very erie setting are well done. Unforgettable is the bad guy, Tuco. He runs crazily looking for the right gravestone. Archie Stanton.
Of course one has to put aside authenticity here and enjoy. The scene of Tuco in the bathtub drilling his would be killer for example.