It's hard to piece togeather info so far, but they have said battles will be bigger with out saying how much bigger, Since Rome the size of battles have only increased marganaly, I can't play Naploelon total war, I just can't play a napoleonic battle with 2500 soldiers, which is bearly a brigade.
They have said that instead of just controling random units, you'll order complete and sevral legions around.
But what that means I have no idea, A roman legion consisted of 1200 skirmishes, 1200 Hastati, 1200 Pincipes and 600 Trairii pluss some 300 light or medium cav. Or about 4400 soldiers, that more then most Total war battles, and now they are saying we are gonna control sevral legions?
I highly doub't we get real legions, I think like 250 soldiers from each soldier type.
I hope they actualy use the right armors and shields ect. in the original rome, the principes and hastati and triarii just looke like later legionares.