I've read One Piece manga around 13 years ago, watched Netflix series last year and bought this game on a 75% discount out of curiosity.
I've played really many games last 5 years and the only one I could compare this one to is Vampire Survivors. Some upgrades, beating hordes of enemies, some rare bosses and very simple graphics and level design. What's actually worser than VS is that in OPPW4 on many maps there's totally no need to think or look at your surroundings - I play without mouse and have a little tougher task rotating camera so I don't do it and I beat almost every map with S(best) grade on normal difficulty.
The good things are atmosphere, music, probably original voice actors, quick story reminder, can be relaxing and dozens of playable characters.
The bad are, in my opinion, standard price, map design, mindless gameplay, graphics look 20 years old. I don't know really what to write here because if I would compare this game to modern AA or even AAA games I would have to begin with enemy AI, no balance, not well thought difficulty growth, very low effort story background, messy optional maps, monotonous gameplay, one type of missions, the only thing you can do in this game is hitting living beings - no talking, no searching, no puzzles, no reason for many obstacles beside being time-eaters.
But I won't say it's the worst game or not worth my time. It can be really fun, same way as I had fun playing lower quality games in my childhood. There's really many possible upgrades, different moves for every character, really many strong opponent types and it's very cheerful, I can reset myself after work or souls.
Fun game but only for fanbase in my opinion. To be honest I would rate it as "One Piece" if I could instead of stars.