There are definitly problems with diplomacy in ciV, whenever someone declares war on me I just don't know why. It feels random, like the game hates me or something. Now I know Firaxis didn't intend for this, and I think they tried really hard to make an AI diplomacy system which felt both realistic and competitive. And I actually think that they achieved this. The problem is that the game doesn't show you how great it's diplomacy is. So when someone declares war on you you have no idea why, even if it's through some brilliant and exciting diplomacy mechanic. What I would suggest Firaxis do is let you see why a civ is hostile or at war with you, say you mouse over the hostile /at war status and it says "You founded these cities too close to us" or "Geneva is our best friend not yours" or even "Your conquest of Cape Town has upset the balance of power". In the words of Duke Leto Atreides; "It is not enough that I govern them well, they must know how well I govern."