Why is Apocalypse Now not regarded as highly as the the Godfather films?

As others are saying here, I would say that it is absolutely held in a similar regard. I've heard plenty of people say that it's the greatest American movie. Granted personally I don't rate any of them quite that high, none of them are even my favorite Coppola movie, but it would not be controversial at all to say that Apocalypse Now is one of the best movies of all time. From the Wikipedia entry:

Apocalypse Now is today widely considered one of the greatest and most influential films ever made. It was nominated for eight Academy Awards at the 52nd Academy Awards, including Best Picture, Best Director (Coppola), and Best Supporting Actor for Duvall, and went on to win for Best Cinematography and Best Sound. It ranked No. 14 in Sight & Sound's greatest films poll in 2012,[9] and No. 6 in the Director's Poll of greatest films of all time.[10] Roger Ebert also included it in his top 10 list of greatest films ever in 2012.[11]

/r/TrueFilm Thread