I have played about 20 hours of the game. Let me tell my Rome 2 campaign story. Start as "British" culture. Conquer british isles as a collective in about 20-30 turns. No tough tough battles but I was still a bit nervous about getting wiped out. Spent 10-15 turns building some armies. Take my best army across the english channel to wreak havoc (or die in a wonderfully horrible blaze of glory)
I didnt need to worry. No one opposed my army.... ALL THE WAY TO ROME.. which I sacked and occupied. Not a single roman army came out to meet me.. and no one attacked after I sacked rome. I turned off the game.
I got fooled again just like Empires. Son of a creek...
http://www.metacritic.com/game/pc/total-war-rome-ii/user-reviews?sort-by=date&num_items=100