Simply one of the best light novels I have ever had the pleasure to read, for those who watched the anime series is very worth going in search of reading the original material.
There are many points that differ from the anime, so I recommend you start reading from the beginning of the story, but if you do not have the patience and desire you can go straight to the end of volume 3 and the beginning of volume 4 which is where the anime ends the adaptation.
About the story: It is very well built and we feel light and willing to continue reading to know what will happen to Ayanokoji and his classmates.
About the characters: One of the few novels that can make you care about practically the whole cast, it is clear that we have established a greater connection with Ayanokoji, since he is the protagonist of the story (one of the great differences of the anime for the novel is in Ayanokoji's thoughts that differ greatly).
About art / illustrations: Simply beautiful to see, nothing to complain about.