In Civ4 to win at Emperor you had to micromanage everything, and even get lucky at few things like starting placement and such... It took me quite a while before getting my first win at Emperor, even now I lose more often then not at Emperor...
In Civ5? My first game was at Prince. I am thinking well it's a new game, it's gonna be tough, so let's start easy... I totally destroyed the AI, absolute piece of cake, no challenge whatsoever, then at King difficulty... same thing... damn it was so easy... ridiculous... I should have jumped to a higher level considering how easy it was at Prince
The game is so simple now. Perhaps it was a good move for Firaxis business wise, I guess there is more potential $$$ to be made from casual players then from the existing hardcore players... So I won't blame them. Many players will like Civ5 much more then Civ4... good for them. But for someone who was used to managing every little aspect of the game in order to get as much of an edge as possible against the AI (only way to win at higher levels)... playing Civ5 is a walk in the park... Ok I was only playing at King level... But the game bored me too much (aside from the Social Policies... I actually really like that part)
anyway... that's my 2 cents... the game is too easy...