You're right about the "childish" part, I did get annoyed with that word as well. It seemed to denote a negative connotation. However, this is a film review and as a critique on a movie, it is usually accepted to add one's own opinion in.
One thing bugged me about this review. You called the director's previous works "childish". That seems to taint the article with your opinion. Maybe a better way to say it would be "his usual works are more geared towards a younger audience" or "he usually aims to please the audience with films of realistic fantasy or silly, goofy plot lines that can make anyone smile."