I expected him to have a change of heart either way. Not for a second did I believe he truly would leave them behind, so I can't really say he redeemed himself as he did what I expected of him. I'm still a bit annoyed that he ran away with the full intention of leaving them behind. Even knowing that the would turn back, because it's his dream to become brave and the timeskip should have made him grow up a bit, I personally think he shouldn't have run away in the first place. Unlike before he now also has some real firepower.
He didn't had to be all overconfident saying he's going to beat the crap out of Trebol, I would have been satisfied if he just had hidden himself not knowing what to do and then appear when the dwarves started their cries. That would have indicated Usopp really had grown as pre timeskip Usopp would have turned around too after those cries. IMO this scene is quite important for Usopp's character development.
He better make Trebol go true some serious pain though >.>