In theory, the new diplomacy system implemented in the new Civ 5 update would only seem to repair a broken system. However, this is not the case. The AI civs behave erratically and unpredictably, making diplomatic moves that completely contradict their supposed motives. For example, while playing as the Romans, Arabia declared war on Russia. Viewing this as an opportunity to expand my territory and help out my Arabian ally (Declaration of Friendship), I too declared war on Russia, capturing Moscow and liberating Russian controlled Arabian cities. Our alliance emerged stronger than ever. However, several turns later, Arabia denounced me as a warmongering menace. This in turn, led every other civ that I was to encounter to denounce me as well, initiating a huge chain of terrible relations, when my only "crime" was coming to the aid of my ally. This new diplomacy seems effective in promise, but is implemented terribly.