While that is more or less true, the arc they are referring to seems to have ended in the very early episodes. As of episode 15, it doesn't seem like it's coming back. Anime News Network describes it best:
"The story follows a boy named Houtarou who is not assertive about getting involved, but was ordered by his older sister to join the classic literature club. In the club, he gets close to the truth about an incident, involving a female member's uncle, which happened 33 years ago. The energy-saving boy is joined by an inquisitive girl in this adolescent mystery." ~ Courtesy of nearly every anime watching website.
Hōtarō Oreki doesn't like to do things that he considers a waste of energy. However, things start to change when he enters high school because even though he does not want to join any non-compulsory school activities, his older sister requested him to join the deserted Classics Club so that it won't get demolished. Unknown to him, another student Eru Chitanda already planned to join; but instead of being free from club obligations, Hōtarō eventually joined as he is strangely unable to refuse nor to escape from Eru's passionate gaze of curiosity. Together with his friends Satoshi and Mayaka, they began to discuss a variety of mysteries in school that only Hōtarō seems to be able to solve; including the mystery that lingered on from Eru's childhood memory.All quotes aside, this anime was what I've been waiting for a long time in the mystery anime genre. While the mysteries might be mundane to a lot of people (Why did the teacher teach a class the wrong work?), the mysteries are designed to be easily followed, just like in books. While watching Hyouka, it reminds me of my childhood, gobbling up any mystery cartoon or book I could find and solving the case with them. I don't like just being an observer; I like to be able to make my own assumptions and guesses with the clues on hand.
Too many mystery anime let you follow the mystery, but then it's solved with some unknown clue, unknown person, or magical powers, which I hate. There's no point in giving you half the clues, then withholding the rest so only the character can do anything. Hyouka gives you every single clue, even if you don't notice it's a clue at first.
Hyouka also has well defined characters… with the exception of Eru Chitanda. By episode 15, you know a lot about each character, what they like, what they don’t like, and what they want to accomplish. Oreki Houtaru claims he wants an average life and hates exerting effort, but keeps at deductions until they are solved. Satoshi Fukube is the always smiling information database, but he seems to have a darker side regarding Oreki. Mayaka Ibara seems at first to be an outspoken character, but it seems she’s not very honest with herself. Eru Chitanda… is very curious. There’s really no character development, so she seems like a really flat character. She can barely do things for herself at all. Needless to day, I don’t like her for that very reason. I'm hoping that Chitanda will show a little more... believable emotion.
If you're looking for an light mystery show without all the blood, gore, and scary things, Hyouka is perfect. It has great potential to be an awesome anime. I'm looking forward to the ending.