Civ4 is a better game, and if you disagree with me... you are wrong.
-Combat has been greatly improved with the addition of ranged units that can attack across multiple hexes and the removal of stacked units, making military based gameplay much more efficient and streamlined.
-The graphics in some areas look a little better, with good civ leader animations during diplomacy.
-There is a good amount of options to choose from when creating a new game, as always.
-More bugs than a locust swarm. It's common for the interface to lock up or for the game to crash completely, especially during multiplayer.
-There is no histograph or recording of any kind at the end of each game. It's very anti climactic to end the game with nothing more than a screen saying "you won," and "your score is 3350."
-No new buildings, no new wonders, only a couple of new units, no new research, no new civilizations, no new improvements, bland music with nothing that stands out, one cinematic in the entire game. The previous Civ had a cinematic everytime you built a Wonder for crying out loud. This is a step in the wrong direction.
-New "city-states" but they're annoying and completely unnecessary. Why would I take the time to go kill barbarians for them when I could just attack and annex the city state itself? Stupid.
-Non existent AI. My workers are so lost they don't even have enough bread crumbs to get home, let alone figure out that my sheep are running wild and there are no roads to my capital. Opposing civs aren't very smart either.
-Advisors are utterly useless and 100% static. They look exactly the same in 4000 BC as they do at 2050 AD. Civ2 had animated advisors and that was in... what year was that again? 1992?
It's obvious that this game's development was rushed and it's important that players don't let Firaxis/2K get away with handing us a game that's only 75% complete and calling it the game of the year again. Because this time it's not.