I like Civ 4 also, I found it to be a very addictive game and spent many hours playing without realising it. As with all the Civ games, the Diplomacy lets it down. I got a bit tired of computers demanding gifts from me and then declaring war when i refused

Even more annoying was what they offered in trade for my discoveries, who would trade Physics for Mysticism?
On the whole, a good game and an improvement over the previous ones...