Have you played Civ3? this game is waaaaay way behind that
Nothing really new here except graphics and sounds. And the worst part is: some good things from previous versions have been removed or changed for the worse.The game designers decided to focus on graphics and make changes where THEY WEREN'T NEEDED!
Honestly, I played one custom game and then I just didn't like to play another one. Some of the things I like in this version are the new graphics and the tech tree navigation, but these improvements don't add much to the game.
War system at this game is poor and unreal. Helicopters are shot down by archers tanks destroyed by macemen. The AI is a horrible mess, it cheats constantly and the combat balance is beyond frustrating. With Civ3 you could simply stack tons of units and more or less win with brute force however this does not work in Civ4, and because of that, you get a lot more ridiculous battle outcomes, Legion vs Modern Armor...you lose? Battleship vs Galleon...you lose?
As a whole, Attacking an enemy civilization requires you to have, and not joking here...you need to have at least 3 times the amount of units per city . So, I found the game so frustrating because I just wouldn't expect that taking an enemy city is almost impossible.
Overall, maybe this game is a good choice for people who didn't play previous versions, but for someone like me that played civ3 more than 500 hours, this game has not much to offer. If I had my time over again I wouldn't have bought it. I'll just go back to playing Civ III.