It's indeed the best Sound Novel i've seen so far. Though the story is not as good as "Kamaitachi No Yoru" series.
This game is more difficult than "Kamaitachi No Yoru" series. (Why I compare them? Because they're all made by Chunsoft and have a lot of similarities.) Some branches are very difficult to reach. The new "108 strange stories" feature force you to pay attention to every sentence in every branch. (Short stories hidden in certain words in the text.)
It's the sound (voice) and graphic that makes the game best.
If you can read Japanese and likes Sound Novel you have to try this game.