The charm and simplicity of it's world is truly what hooks people in. The fact that we manage to explore more about the school, the vision of the world about the magic, the relationship between the characters and their respective personalities are things that the OVAs made an erase, showing the potential this kind of story had, and the anime is there to show it in a great, cute and funny way.
A thing we haven't seen in anime for years, a white humour comedy that is not filled with moe or sex appeal overdose that most of animes nowdays try to get stuck in our throats.
If you are looking for a great epic fantasy story, go look somewhere else, if you are looking for a "Anime Harry Potter", this is not what you are looking for either like many people try to say about this anime [Altho it shares some similarities that made me draw a smile in my face].
By the time i'm writing this review the show hasn't ended yet, but it sure gives us a lot of promises without the need of a complex story, but an amazing world, and characters that truly shine, and that everybody can enjoy.