Good balance amongst the factions, the AI even attacked me that game, and the factions have a great 'feel'/consistency/logic to them.
I second this. The factions are well thought out. They provide a mix of benefits and drawbacks that work to their advantage (or otherwise) in different games, meaning you can't count on one being significantly better than the others. The lore is attractive, and the visuals work, too. The added faction heroes aren't the least of its attractions, either, and the Reliquary is a delight offering strategic choices to-be-made that just might blow up in your face. Which is the way I like it.
I'm serious, this mod is very professional, reminding me of FFH2 and the like for Civ4 (and you know what happened to that guy/those guys!).
Check out the Master of Mana mod, if you're still into Civ IV. Takes over from where FFH2 left off--all that wonderful lore--and the computer AI knows beter this time what to build, and when. A real challenge, even on lower difficulty levels.