Using an idol as a character to sell tickets with a lot of music in a One Piece movie pissed some people off.
If you wanted a more traditional One Piece movie about the crew fighting an enemy, it's a bad movie. If you wanted something really different, it brings a lot to the table.
It's always a risk to make a movie like this, but, obviously it worked out for them. Hope Ado enjoyed the experience, it's a unique opportunity for an Idol to be the face of an anime movie like this.