That quite a good ending.
In the end Uruk's destruction came to pass as Gilgamesh saw, but humanity survived the conflict to rebuild a new elsewhere. I didn't expect Quetz to have lived through literally going out in blaze of glory but given the last two sort had nearly everyone except for Eresh BSing their way back its par course. I suppose.
Everyone essentially got the send off they needed tho kinda what's gonna happen to underworld without Eresh there to administrate anymore...
Anyway, I rank this as definitely one of the better Fate adaptation. In fact I think enjoyed spin-offs stories (Zero, Apocalypse, Case Files and now this) than I have the main stuff except Heaven Feel's movies which is arguably the best of Fate for me. I supposed more due original series being an VN compared to the much more straightforward side material.