Civilization IV is a great improvement on the previous games in the series, and I highly recommend it to everyone. I did notice some annoying video issues which are apparently being addressed by a patch released a couple of weeks ago:
Some of the highlights include multiple AI improvements and tweaks, worker behavior tweaks, MANY game play improvements (ex Animal Husbandry reveals horses), promotion tweaks, a softer pillage sound (requested by many, many people), fixed diplomatic exploits (gold for gold, peace treaty exploit), multiplayer tweaks (Hot seat, Lobby, etc.), memory, caching and performance improvements, etc. There were also a number of video card specific fixes.
