This is an animation film about lost heroes resuming their service again to stop evil plots being implemented.
I think the runaway success of this film is that the film's lead heroes are very everyday. The family is portrayed to be heroes who have had their glorious days but got disgraced because of a series of negative incidents. They then choose to have a family life and stay away from the limelight. They are reluctant to use their supernatural powers, and only uses them when the situation gets out of hand. This key point is radically different to most superhero movies, where the heroes have always been glorious heroes and will forever be glorious heroes. In this movie, the heroes fall and then rise back up again, creating a positive message for kids.
Apart from this fundamental difference from other superhero movies, it also has a great story. It also has cute and attractive animation. This film really deserves the attention and praise, and cannot simply be attributed to be popular because it is an animation.