I love this kind of story where you want to guess what is really happening and what will come next, but even when you can guess some of the story, for most of it you won't have a clue of why this or that character is doing something, most of the time there is a deeper meaning.
The cast is great, they make it dark, funny and emotional.
I have seen a lot of dramas, but there aren't a lot I would recommend from the bottom of my heart if you want to watch a great story. This one and Nobunaga Concerto are the ones that I have liked the most, since even when the story is simple, it gets deeper and different from other dramas.