Its pretty good, I think the deck is stacked a bit too much against Rome. I am playing Western Rome on kings now, was having a very smooth sailing. The first few turns were rough, but after 20 turns or so I counterattacked (there must be a lame "the empire strikes back" pun in there). Liberated the few cities the Franks and Celts took, liberated my dumbass Byzantine's cities as well. Then went on the offensive vs. the Franks and Vandals, started capturing their cities as well.
Then I had to adopt the policy which brought my happiness under 10. With the barbarians adopting the +50 % if adjacent combat unit, that means my units have an 83 % disadvantage, which is starting to get a bit frustrating, even more againt the Celts. I have 20 turns left, and have the empire in its original size + vandal territory, so I should be able to win quite easily, but its going to cost me more than a few units. I think there could have been more balance there, especially on the fact that there is nothing you can do about the hapiness thing.