Story was quite good but it was written by the author to early as author don't about the future plot of One Piece so he has to simontaniously including the ongoing story in FF.
there are many plot holes author has tried his best to fill the holes.
For me I don't like story when MC is in one piece it is boring in one piece
but FF got very intrusting when MC trevel to different worlds
Familiar of zero ( It's ok )[ heart ]
Mushoku Tensei ( I loved it )[ magic , Sword ]
Re:zero ( Good )[ Divine Protection ]
Akame ga Kill! ( it's ok )[ Teigu ]
Danmachi ( Gooood )[ Divine Protection ]
JUST SKIP ONE PIECE AND READ IN STORY