You beat me to this answer. I knew it was going to be good because of its phenomenal word of mouth and I was still surprised. There are so many cool details that no one will notice on a first watch, but show how much care the creators had for it. By way of example, Death can be seen in the crowd during the opening giant fight (he was there to witness each frivolous end, after all), and the numbered cards denoting each death have the silhouette of Death holding his shotels in the corners.