The show is very interesting in historical and political context. The producers are of a generation that spent their childhood during the war, and they projected onto Earth the image of the ideal, strong Imperial Japan that they saw from their child's point of view. Gamilas is the image of the bad Imperial Japan they were forced into after the war. The point of the story is that both images are wrong. Earth would have been destroyed without Iskandar's help and Yamato would never have defeated Domel without plot-armour. Gamilas had no choice but to invade space for its own survival.
It was persuasive that Yamato was the first anime made to be enjoyed by adults as well as children. Children of the time would have purely enjoyed watching Yamato defeat Gamilas, while their parents would have felt sympathy for the dying Gamilas because of their wartime experiences.

General Domel is my favourite character.