I think that when a book series is different and successful such that it creates its own mini genre that this is only a good thing. Just like Harry Potter which broke publishing notions that kids won’t read very, very thick books, Diary of a Wimpy Kid series also got kids wildly excited to read. And though the lead character is a boy, girls were also reading this series in droves. I also think that the graphics helped to legitimize graphic novels from comic book status to it-counts-for-your-reading-log status. In any case, if your child needs more Diary of a Wimpy Kid but has read all the books, here are more options including some that skew younger and older.