For the first two minutes of the "Apocalypse Now" I would forgive all the rest. But I won't forgive one thing - the ending.
Because no one pays attention how strong the original ending of "Heart of Darkness" is.
'Repeat them,' she said in a heart-broken tone.
"I was on the point of crying at her, 'Don't you hear them?' The dusk
was repeating them in a persistent whisper all around us, in a whisper
that seemed to swell menacingly like the first whisper of a rising wind.
'The horror! The horror!'
'His last word--to live with,' she murmured.
I pulled myself together and spoke slowly.
'The last word he pronounced was--your name.'
Coppola is fascinated by the darkness. Conrad is not.
And Conrad's hero is strong enough to sentence Kurtz into oblivion, to see clearly that all his quest ended in nothing. The ivory that Kurtz gathered is all rotten. And the truth that he found is not worth telling to a person that loved him.
There are nothing to learn there.
And that's why a total majority of war/anti-war fiction is so utterly boring.
War makes people older, not wiser. Which is shadowed by the fact that most soldiers come to a war in the age when they do (on average) become wiser.