What does it mean to be human? To be a ghoul? Those are the questions Tokyo Ghoul raises once you inevitably (if you're like me) get hooked on it.
There's a decisive battle between the ghoul and human aspect of our protagonist; one who was turned into a ghoul against his will; one who struggles with accepting who he has become. You may find yourself annoyed with Kaneki Ken but after what he's been through, you may find yourself doing the same thing. It's so morose that you can't help but wonder what did these people do to deserve such tragedy?
It's not a complex thing to understand, this show, but it will have you thinking. And enjoying it.