Honestly, characters really are the most important facet to a story. Jack Sparrow practically made Pirates of the Caribbean. The Last Airbender movie failed because M. Night ignored the fan-base's love of the characters. While all pieces of a story are important, the characters are the authors, and Hyouka is clearly written by the characters.
Moreover, I would like to note how clever each mystery is. Granted, no dark murders or kidnappings have appeared on campus, but seeing how I am still watching, the author works with the "mundane" very well. Also, I am not sure that the mysteries are going to remain so light. After all, Chi's uncle has been missing for seven years, and for those of you who have gotten this far, "I scream" sounds a little ominous. I am fascinated to see where the overall plot goes.
The art and the sound are wonderful as well - I love the sequences when Chi's curiosity takes Oreki by surprise.
