In 480 BC on the coast of Greece, the invading Persian army was stopped for three days by 300 Spartans and allies on land, and Athenian led naval vessels on the sea. The last stand of the 300 was well remembered and served as a rallying point that stirred the previously independent city states into becoming Greek, one and all.
In university I did one of my upper level long papers on Thermopylae and the effect it had on Greece. It isn't easily researched because the work by Herodotus was considerably shit upon. Later historians challenged his words, and assumed it was all propaganda and fiction. But, it probably had as much truth as falsehood, since Herodotus did interview people who had seen the event, and he had some knowledge from others who had seen the impact of the event.
Frank Miller chose to tell a story that was fictionalizing the event, so, he chose to take moments known, and fill in the blanks. He made some characters uglier, some sexier, some more violent. That is, he wrote a story. The characters on each side are brought to life in his work, first in comics, then in an amazing film. Some people view the Spartans as fascist or ancient predecessors of Nazis. But, telling the story of the 300 Spartans without moralizing over the Spartans world led many to chastise Miller.
His work was fiction, but it captured the martial spirit of the moment, and I love it. Others can sit and judge, I choose to enjoy and educate myself about the reality with other accounts. I don't really know why people can't do the same thing. The Graphic novel, or tpb collecting all the comics I prefer over the movie, but, that is just the kind of fella I am.
For centuries scholars and readers assumed the story of the Trojan war was a myth or legend. The story was about how a prince named Paris eloped/kidnapped a beautiful queen/princess Helen, and the people of the princess's homeland (Sparta) followed her to return her. Troy and Greek states though DID go to war. The site of Troy was proven to exist by an amateur archeologist from Germany, Heinrich Schliemann. His methods were regrettable, yet, they proved that myth and legends are often born from reality.
Eric Shanower tells an enormously different story than Miller, in a far different style. He tells the fiction of the story of the Trojan war, told first by the amazing blind poet Homer. Shanower's art is unforgettable, perfect for the story, and emotive, and the writing is emotionally moving, and beautiful.
The Graphic Universe is good, but does not compare in any way, shape, or form, to the previous two series. However, if you have a child who is learning about Greece, it would be an amazing way to introduce them and further their knowledge. (And by no means on simply this subject).
I haven't read any work from this series. Therefore, I can't outright recommend it, but I can say from the looks of it, it would be right up the alley of anyone interested in the mythic history of the Gods of Ancient Greece.