Story: 5/10. I have to say, the overarching metaplot of One Piece is actually quite interesting, and each arc contributes to adding another piece into the puzzle to allow the reader a deeper view into the world and end-goal of OP. Unfortunately, that interesting plot is hampered by abhorrent pacing. Not to mention the repetitive formula that is employed 90% of the time: sail to an island -> find the people are oppressed -> crew fights main bad -> some character has a dramatic backstory -> crew wins and saves the day -> rinse and repeat.

Some will say "formulaic is fine because there's a ton of different elements behind that formula". No, not really. If you read a single One Piece arc you'll know how all of them go 70% of the time. The other 20% might be changing how the side characters look, or changing the locale, but it's more or less the same. Moreover, there's no variety in how these situations play out; it will always end with a climax of the strawhats getting separated in some way, the minor ones fighting the minor villains and Luffy fighting the main bad and (probably) winning, and if he doesn't win the first time, he'll win in the near future after some deus ex machina powerup. It's a shame because if One Piece actually dried to diversify its arcs and not have them play out the same way every single time, it could easily skyrocket in quality.

The other 10% of the time is the actually interesting backstories we get, but they don't really add value because the character who gets the backstory ends up becoming a bland set piece as soon as the arc is over.

Art: 7/10. Oda is clearly a good artist, but the art style itself doesn't resonate well with me. I find it goofy and hard to take seriously.

Character: 2/10. I find the characters of OP unfortunately bland. They have moments in the spotlight, and each one typically gets an arc in which they're the main focus and get to shine. Outside of that arc, however, they are just a caricature of 1-2 personality traits; one likes to flirt with women and cook, the other likes to just lounge around and say a cool line once in a while, etc.

Moreover, once I was like 200 chapters deep into this series I realized, these characters don't change or offer anything interesting at all. I've read 30 chapters of manga with more character depth, exploration and nuance than these guys. None of them are memorable, charismatic or interesting in any way. Around 400 chapters in is when maybe ONE character got some interesting development, but then again...when it takes 2x some other manga's runtime to stuff some barebones depth, you're doing something wrong and your manga is bloated to all hell.

Enjoyment: 5/10. It was ok. I really only enjoyed a handful of arcs out of the 500+ chapters I read. I'd say the best were Arlong Park, Skypiea and Water 7. But it never captivated me like it seems to do with everyone, so I know I'm in the minority. Perhaps it's because I didn't grow up with the series and don't have those rose tinted glasses.

Overall: 5/10. One Piece is one of the most mediocre shounen I have ever read. It has tons of potential: great art, coherent and expansive world-building, and a very consistent passion behind the series that has persisted for decades upon decades. However, it really holds itself back with shallow, static characters, a repetitive formula that has lost its luster and an unfortunate tendency to always play it safe.