Hello, well first can you please introduce yourself in a new thread there? http://sora-to-kasai.forums-actifs.com/f1-presentation
I found the association fresh, the beginning was building up a nice atmosphere but I think you kind of lost it after the song takes off. The fights look a bit too random, the narration is getting a bit messy, I think you should have focused only on Luffy with more calls to Ace, as a viewer it was too easy to forget why they are fighting and that's a problem.
As for the technical side, the inspiration from Naoya might be a bit too clear, especially because of the HxH scenes that didn't work out for me. But it's cool that you made the effort to mention him o/
You are overusing the overlays you're using and don't really match neither the mood nor the synch most of the time. You have to restrain yourself a bit with them or find/make new ones more often.
At 2:52 the Brook masks looks quite ugly in comparison with the others, it's important not to neglect details like these imo.
So indeed, you still lack experience but nevertheless, this is an interesting project for One Piece and I'm looking forward to watching your next work. Keep it up!