It's less a mod than a technology showcase. From what I know it was written by one of the devs to demonstrate that stuff like this can be done and is not really maintained or evloved any further.
What do I think of it? It's slow. Seriously slow. Python overheads for doing all that nonstandart graphic and AI are huge and are killing performance on big maps and in late game. It's also pretty underwhelming when it comes to immersion. Sure, it does look and play different at first, but there's not much going on on the map, the tech tree is short and shallow, unit choice is small and doesn't differ between the factions and generaly it gets boring pretty soon. It has, as a mod, many more flaws but its an excellent showcase, so it does what it was meant to do.
AI is decent, as far as I can tell, it does it's job without fuss. But that's on small maps with few players, due to performance I didn't really play anything big. Diplomacy is neliglible, basic civ stuff you can live without with no fireworks anywhere.
How it's different from GalCiv? Better (or rather more interesting, if unbalanced) planet system building options but: very limited ship choice and in comparison poor AI/diplomacy/economy/research. No random events, no customisation, no minor civs, really annoying barbarians, poor background lore, feature poor maps. But again, can't really compare a mod written to demonstrate platform features with full-fledged game.
Suggestions? Try MoO2 or StarTrek mod. Both use Final Frontier as an engine, both make it actualy playable on bigger maps (yay for optimisations), both were in active development last time I checked and generaly are more fun than basic FF. You can find them (and few more interesting mods) on civfanatics.
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