Just try it.
I remember traveling to Japan once when I was little and spotting tons of One Piece merchandise. Uniqlo sold t-shirts with the bounty posters, the amusement park had stands just for Chopper bath towels and so on.
I found it all to be stupid.
I thought the characters looked grossly exaggerated (though, to be fair, the picture I found most disturbing was Sanjis bounty poster, which is quite funny in hindsight) and as the tiny little feminist I once was, I didn't really like the fact that Namis bounty was the lowest, excluding the pink-hatted whatever it was, whom I was convinced would have the same amount of intelligence as GIR and intelligibility as that of a shoe.
God damn was I wrong.
Flash forward a few years, and less tiny, less feministic me is welcoming my dad home from a business trip to Japan. By that time, I had gotten hooked on manga and anime, effortlessly and eagerly reading a hundred chapters within 1 or 2 days. Dad told me he had bought me a new manga and so he presented onto me, One Piece. I picked it up, remembering it as the weird franchise that I stumbled upon in Japan. I was slightly reluctant but luckily, openminded and so I sat down and began reading. Then I quietly looked up the rest of the chapters online and continued reading. And reading. And reading. And by bed time that day, I had read the first 150 chapters of One Piece.
It was magical.
So screw all that about the cartoonish art style and exaggerated features and "how it isn't for everyone". Just try it. If you don't like it, you simply don't, but it is the worlds most sold manga for a reason. If you like it, like me and millions of other people, enjoy. It's a page turner of Harry Potter level.
Oh, and the Fishman Island arc? It's mostly just to show off all their new powers, the villains are cannon fodder. But read it anyways, it has a few important plot points and the attacks themselves are worth chocolate. Lots of it.