My impression - both from my own play and other people's comments - is that playing on a normal map with 8 civs gives one a radically different playing experience than playing on a large (or huge) map with 8 civs. I get the impression that the people complaining about lack of AI aggressiveness are playing on the bigger maps. My experience so far is that the AI is VERY agressive on a normal map with 8 civs.