It's basically the oldest recorded story of any kind, and that gives it a weird sort of prominence. Gilgamesh feels like a prototype of Achilles in a lot of ways. The ultimate, hubristic badass, caught up in a quest for masculine honor which eventually breaks and humbles him after he looses his closest friend. Physical strength and sexual prowess are the end-all-be-all of these people's lives. Yet there is also this incredibly dark, world-weary sensibility at play: no matter how many monsters they kill or seven day sexual marathons they participate in, death is going to get them in the end, and they sure can't seem to forget it. It doesn't have the consistently beautiful writing of later epics, but at times it's actually pretty poignant, especially towards the end when things start to get really sad and brooding. Goes to show you, civilization was old before it was ever young.