The books are often described as boys’ adventures with a girl as the main character, not unlike The Hunger Games or The Divergent series. (Although those are completely different books, Superhelden.nl tends to attract the same kind of readers.) In the Netherlands the readers are about 60% girls, from age 9 to 17, and boys, from age 11 to 17. At the same time, the books are very popular with adults who love books like Harry Potter, the aforementioned Hunger Games, The Fault in Our Stars, The Maze Runner, and Miss Peregrine’s Home for Peculiar Children.
The books have many intertwining storylines and tend to attract readers from all sections of society who are used to books, TV-series and/or movies that have those same qualities. (Think series like Homeland, The Vampire Diaries, Person of Interest, Games of Thrones, etc.—but you know, for kids—and movies like The Hunger Games, The Divergent series, Fast and the Furious, etc.)
Funnily enough this doesn’t necessarily mean that readers need to be highly educated, as the books have readers at upper primary school, the HAVO/VWO (higher secondary professional education), as well as at the VMBO (higher secondary professional education). The books are highly recommended by teachers and parents alike for kids with dyslexia. We have dozens of e-mails from children, teachers and parents, all saying the same thing: I/my son/daughter/my pupil did not read, but I/they devour Superhelden.nl.