I played last night, went up through 1500... Great scenario.
Some notes... I played as Byzantium
*You have "Bari" as a city on the NE coast of Sicily. It should be, more likely, Messina. Bari is on the mainland, around the top of the heel on the east coast.
*There are several Pedia issues... these are an easy fix
*I lost 4 cities before peace with most, the Abbassids would only give peace at the price of a city, so the fighting carried on. This seemed reasonable enough. I even took Rome! Perhaps the Lombards could have a minor invasion force on the Italian Peninsula also, to stop Byzantium from taking the offensive there?
*Seeing as how Byzantium and the Islamic world were on the cutting edge of techs at the time, I was surprised at the low levels of units, and no gunpowder units. I mean, by 1453, you know the history I am sure... huge cannons, etc.
*Surely you can get the buttons/symbols for the religions to be more accurate? The promotions with the three medic shields... I am sure you could change those to better buttons also...
*On the first turn, every Muslim nation except the Abbasids converted Orthodox Christianity. To counter this, perhaps you could take Orthodoxy out of all those cities they took from the Byzantines? I understand there was definitely a huge Orthodox presence, but for game mechanics, perhaps just the ruling state religion should be present in most cities...
*I think, and I don't know if this is possible, that Byzantium should have the ability to see the eastern world, since it had surely had maps, and basically just lost a lot of that land.
*The starting date... the Muslims were not so broadly spread out at that time (If, indeed it was 660AD, I actually didn't look, just started playing away!). Perhaps they could have huge invasion armies as a better reflection.