This drama is a rare one amongst those so called Chinese Costume drama (be it wuxia, xianxia, etc.) It reminds me of the old times Chinese martial arts series, which is great!
It is realistic: People getting cut with swords / having injuries, realistically will lost blood and died. Unlike most of nowadays series, which usually the people are like invincible never died, sliced, stabbed many times and can walk happily just cured with inner strength will do!
Another good thing with this series is the sword fighting. This proven, no need extravagating Visual Effects can make a series beautiful. This is the main thing missing on so many current Chinese Costume drama out there.
And lastly of course the story line, is refreshing to have a detective story that resembling Agatha Christie style.