I really love the maps Oda adds in each arc. It makes each story feel like an infiltration mission, and helps the worldbuilding at the same time. Also helps that it's a pirate manga and is all about following maps to treasure and adventure. This is the good shit right here:
The thing people don't seem to understand about Fishman Island is that it's supposed to be a "reintroduction" arc of sorts. LOTS of callbacks to East Blue, Arlong, and a massive buildup to the crew coming along and stomping the villains with ease.
I personally loved it. The prophecy about Luffy destroying the island, the Noah, the finale with Red Hawk and the Sea Kings, the introduction of Poseidon, the stinger with Big Mom at the end, it was awesome from a lore perspective. And that art, oh man, that art! The whole place looked like an underwater carnival.
And then you had awesome set pieces like Ryuguu Palace (will take this down if it counts as a scan, I don't think it does though):
A good arc all around IMO. People were coming off of the high of Marineford and expected something more, so I think the "reset" is what makes it less well regarded than it should be.
Skypiea is another of my favorite arcs, and it's also not very well regarded. They're two of the most fantastical locations in the series and have comparatively few classic shonen battles, but their sense of adventure and wonder is through the roof. Above the sky and beneath the sea being similar, huh, imagine that.
