Great plot. Great acting. Great music. And one of the very Great endings to a Great film. The last 20 minutes are just fantastic cinema.
It builds momentum wonderfully. Blondie and Tuco are sufficiently ambiguous characters. Angel Eyes is just plain bad, beguilingly so.
It can often seem clichéd until you realise that you are watching the original, it has spawned so many copies but none get close to this masterpiece. Morricone's music is an essential 4th major character, again being an original that defines the genre.
A genuine piece of cinematic history and deservedly so.