It's not hard to locate the two biggest problems with Hyouka, neither of which have anything to do with the actual quality of the production:
Problem the first: The show appears to be about solving extremely mundane mysteries which have no inherent 'weight' to them - nothing that would make an audience care about how they are resolved.
Detective stories aren't just popular because detective-type characters demonstrate their cognitive abilities to decipher mysteries. They're popular because crime and murder are interesting topics. When someone has been murdered most people would say that it's really important to know who did it and why. When someone borrows a book regularly from a library, or opens their windows to let air out a room, it doesn't engender the same interest.
Well, I think you hit indirectly on the key point of whether or not this show will work for someone. For this show, I think the primary draw is being able to identify personally with the characters, and NOT the mysteries themselves. This certainly makes it a different paradigm from the typical mystery show.
I wonder if the reason the show works for someone like me is because, when I was younger, I always had an overactive imagination. Not necessarily in the context of solving mundane mysteries, but like this show, I had a habit of "enhancing" everyday events with the power of my imagination.
Problem the second: Our protagonist isn't just boring by virtue of being a flat character, he's boring because that's his goal in life. Branduil, perhaps correctly, points out that this is the point of the show, but it still doesn't make watching the show any more tolerable.
Perhaps they're will be some radical event which forces him to alter his position on life at some point in the future, but it doesn't seem like that's going to happen anytime soon based on what I've seen so far.
I don't think the goal of the show is to be boring, but it can certainly work out that way for people.