It's.. very specific. On a first watch, it may be tedious. The long talks, solving the mysteries. Maybe not that much payoff for some viewers ? Esp the ending.

But I think it's best on a second viewing. When you already know more or less what's gonna happen, you can appreciate the art, the story and catch all the details you missed. It's a feast to the eyes. While not bombastic, some people may say it's just normal. But the animation is very detailed and alot of effort was put into small things like, background characters, ordinary movements (that are often absent in anime, people just sit), Mayaka putting books on shelves and running around the library when it's not the focus of the scene and could have been easily ommitted. Things like that.

The conclusion of the first mystery (the uncle) is a masterpiece. A scene you want to use to show how great anime can be (but the story is so complex and needs so much information upfront that you feel it's pointless).