The art alone makes it worth reading. The use of lines of various thickness as a way to add shadows to every element and make them contrast more with each other is top notch, and the covers use lots of colors in a way that makes them resemble watercolor paintings a bit (and gives the while manga a very special style).
The story isn't bad either. I would describe it as a soap opera where on every arc Hanako, Nene and Kou deal with completely different ghosts while learning more about their sad pasts (and about Hanako's past). The best parts definitively are the interaction between characters. You can feel how they genuinely worry for each other (to the point where it can be dangerous), and the way they banter each other even during the saddest moments keep the manga from becoming a complete melodrama.
The anime is alright. They nailed it with the art style, voices (they are a bit weak in the first episodes, but eventually they get much better) and music (just check the ending theme https://www.youtube.com/watch?v=FShmu31ZZZs
), but the rush of making everything fit in 12 episodes and the overall lack of budget ended up butchering the plot (chapters omitted, order of events altered), near zero animation (they "solved" it by making the anime look like colored manga pages) and lots of QUALITY (specially after EP4). The QUALITY is mostly solved with the BD release, but if you are a fan of faithful adaptations this one will make you angry.