The AI is the major weekness in the game, its to easy to defeat and too unpredictable to bother with much in the way of diplomacy, basicaly any nation which border you will end up at war with you no matter how much you help them out.

the only time i have difficulty is when the faction lacks cavalry and i cant do the pin and flank with the cavalry.

or whe you see there general charging headlong for you spearmen, has the mentality of a world war one commander, Charge,and if it doesnt work the first few times its bound to work later

I hope they live up to there promises, time will tell.