It's a One Piece movie that does something different with it being more of a musical centred on the new character Uta, Shank's daughter. It's not action-heavy like previous movies. Uta herself is a complex character with clear mental issues, which is not what you usually see in One Piece. It delivers great songs, good animation and an emotional yet dark story. The last 20 minutes of this film are stellar!
Don't come into this one expecting something similar to 'Strong World' or 'Film Z'. This is a unique experience for One Piece in general. I personally found it a fun watch but I understand that this film might be divisive for One Piece fans.