This have been the mother of flashbacks. First we got his flashback with Shanks and thought that this is why he became a pirate. Then we got the flashback with him and Garp and thought that this is where he got his determination, strength, endurance, resilience and will to live. And now we got this that showed that this was just the foundation to that and his real resolve to become a pirate was his experience and promise with Sado and Ace. Same for all of his strengths. And his protectiveness of nakama.

And we also got to see what Ace and Luffy's story was. And we got to know the reason why Ace left to become a pirate before Luffy did. And we got this new character named Sado. Who might still be alive and might potentially show up as a member of Dragon's crew or a pirate himself. Although i feel it in my gut that he is actually dead.

And even though i though both Zoro and Sanji's (and Nami's to some extent too) flashbacks carried a lot of emotions and impact, this one toppled it all.

Also do you guys think that Ace got his smiley and sad face on his hat as a tribute to Sabo and Luffy, since Sabo always smiled and Luffy always cried?