The storyline is intriguing and unique. The plot moves at the perfect rate, almost no filler. This show kept me guessing and I simply couldn't turn it off. I had to know why a character was acting a certain way, what their motives were, and what they were doing next.
The characters are flawless. They're diverse and well-rounded. There's no one-dimensional characters here. The "bad guys" have good qualities, and the "good guys" have done terrible, atrocious things. Nothing is black-and-white. I found myself getting attached to all of them in different ways, without realizing it until it had already happened.
The intercharacter relationships are beautiful and deep. You can feel the bonds between them.
This anime has it all. Depth, humor, seriousness, sorrow, joy, frustration, love. It looks into what it means to be human, and what some people will do to preserve the notion of humanity. It also seriously touches on the issue of what makes a family a "family" and it does it in a subtle and not at all cliche way.
I would recommend this anime to everyone. Period.
