Good for kids but lacked the nostalgia of characters Shark Boy and Lava Girl that the previous generation grew up with. They acted nothing like themselves and the adults made little appearance.
The movie implies that there have been many generations of superheroes and that Shark Boy and Lava Girl were trained to be superheroes. This makes no sense next to Shark Boy and Lava Girl and their original backstory as well as the ending of their movie.
This is in no way a movie for the whole family, more like something for children to watch while their parents leave to finish something else. Mediocre acting and a bad storyline.