This is a breathtaking sequence, it doesn't even look like One Piece on first glance.
The symbolism is obvious, with soaring towards the top the victor and King plummeting to the bottom the loser. Their flashbacks show that it was a battle of wills, which were for both to never lose again for the sake of their captain. Zoro's will was just stronger in the end.
King of Hell will take some getting use to. Pirate Hunter made sense on multiple levels, and still applies now. But King of Hell? Just seems too far on the nose. We'll see how it develops, after all Enma was the ruler of Onis. And the main antagonist of the arc is an Oni. Oda doesn't do these things for no reason.
Usopp's moment with the Samurai looks like the highlight, though. Usopp may be claiming himself a coward, but his warrior spirit is shining by cherishing and protecting the lives of the Samurai who are willing to take their's.