Some of the stuff such as more units, civs, techs, resources, wonders, etc is really just eye candy (which is OK) but doesn't fundamentally improve the game for me.
We asked for disasters (and finally we got em back)
For me, the success or failure of this XP will be determined by how well these changes work:
More Government Types: - Fascism, Feudalism, Tribal Council, and Imperialism are just a few of the new ways to rule your people.
More Unit Abilities - Including Stealth Attack, Enslavement, and other bonus attack modifiers such as damage multipliers can now be applied to units
More Attributes - Including two new Civ-Types: Agricultural and Seafaring
We tried stealth and colourless land units 1 year ago and the AI couldnt really handle them. Hopefully the combat changes will be significant.