While it may not be able to compete graphically with newer Civilization games, it still keeps it's charm after all these years.
Because it is a Voxel/Sprite based game, making models is simple enough(and I say that due to me seeing a good 8-10 models pumped out a month compared to Civ IV and CIv V's model sections on Civ Fanatics)
the scenario editor is where all the fun is though, want to make a scenario based on a Colonial Marine Invasion of Xenomorph Prime? DO IT!, want to have Skynet and the Resistance fight a war ALL OVER THE GLOBE?! do it! ever wondered how the UNSC would fare against the Imperium of Man or the Galactic Empire? you can do it!
there is so much can be done with the scenario editor, and if that's not enough for you, some wonderful programmers at CivFanatics have made an expanded Civ scenario editor.