I'm a little disappointed... maybe they shouldn't have leaked whatever they have until now. Seems like Espionage and religion, things we have already gotten a taste of in the previous civ, are the only brand new features.... with some tweaks here and there. Who knows if the game play will even be significantly better, or more immersing... after several play throughs.
I was surprised in terms of the content and nine new civs, but I guess that is pretty standard for a full blown expansion pack.
Overall, I think the expansion will allow the player to explore more avenues, but I still believe the depth will be lacking, even if the combat and the diplomacy drastically improve. It can even be worse with some of the new features so fingers crossed.
Outside of an improved AI, I am a sucker for heavy content and as many avenues as possible, so as long as we continue to get new techs, units, resources, buildings, etc, that is one of the main things for me. More features the better so long as the game play doesn't suffer.