I'ts still pretty easy, I've played everything from Shogun to this, and I've always played on the hardest difficulty

User Rating: 8.9 | Rome: Total War Barbarian Invasion PC
The difficulty increase is good, but with the leave the home and stuff, a single Goth town of Dacia will withstand the hole Huns and Vandals invasion, killed 10.000 of them with only one town on medium difficulty, so they never got to Rome lol
The difficulty can still go up, don't have a problem with it.

The focus more on battles and less provinces to control is good, never liked a big empire anyway.
The cavalry is nice, AI has improved but it's not that smart, so 2 warlords on a ambush mission will decimate the enemy lol.
It's all in the stalking tactics, all in all, pretty nice.