Fairly rated series.
It receives a fair amount of criticism for its plot conveniences, fake outs, fan service, sexism, mediocre to down right awful pacing, and cardboard character writing for most characters post time skip.
However, there's no doubt that a lot of its hype is highly warranted. How many stories can keep things interesting for 30 years straight, most of the other highly rated series are either the size of a Onepiece saga, or decline after the first few arcs. It is just incredibly difficult and special to keep writing a story, with an overarching plot and world size that massive while keeping plot holes at a minimum that the story still makes sense. Miura couldn't keep up with Berserk. Hunter x Hunter and Jojo follow a variety of storylines with no clear overarching plot. Full metal alchemist was probably the size of Enies Lobby. Chainsawman isn't as good in the 2nd half and it's little more than 100 chapters. It's is insane that Oda could keep up for 30 years straight and still deliver quality arcs like egghead and boss the manga charts. Don't compare a One piece arc with other series on it's own, every arc a small piece of a larger puzzle. And while post-time skip is full of questionable stuff, many of it, like character focus, is usually lost as a side effect of the story focusing on other aspects (I.e. world building)