Isn't there a problem that a huge number of mammoth tanks will NOT solve?
*What? My credit card is empty? But see, there, the mammoth tank? I bet you will give me the stuff for free.
*What? I only got 40 % of the votes? Who cares, I got the tanks, so hand me the presidential seat!
*What? The guy drives a Ferrari and all the chicks dig him? Well, let's see how many dig me when I cruise through the neighborhood in my new Mammoth tank!
Anyways, Civ4 is a rather decent game. Lots of options, and one thing I consider both a boon and a curse: war is difficult. In all the previous Civilization games, you could just roll over the opposition, even Alpha Centauri supported 'shoot first, ask later'. Not so Civilization 4 - cities are difficult to take, sieges protracted, army expensive, and longbowmen holed up in a city on a hill just a plain pain in the ass. And, save-loading doesn't work (the horror! the horror!).
Also, you cannot use roads on your opponent's territory, meaning that your army moves like a slug. I don't know who is going to keep my war elephant from using the road, but... Sid thought it would be funnier so.
What does it mean for the gamer? More thinking, first. Plus, restarting a game when he's stuck on a crappy piece of the continent with a computer on far superior ground, usually.
Other than that, the culture system is interesting, the diplomacy OK (watch out for the disbelievers! You're bound to have bad relationships with people of a different faith) and the social order system (divided into Government, Legal, Labor, Religion...) quite alright. A certain bias is visible, as Representative and Universal Suffrage systems are far superior in game-mechanics to Monarchy and Police States...
All in all: Echo recommends.