Started a few days ago on V4, with my favorites from the past versions, Romuli. Unfortunately, things are not so good as it was in V3. Somehow, AI has vast amount of money and huge armies, while I barely struggle to field one full roster army with my finances. On top of that Barka is expanding aggressively in Hesperos. while Dominion can quickly overrun the cities close to my territories (Heraclea). I suspect there are some scripts to give AI extra armies and maybe cash too.
Regardless, I kind of handled them, as in after capturing Rhegium and Capua moved fast on Hesperos, destroyed 3 Barka armies and captured 3 cities in a very short time (Elysium, Colchis and Troy). Barka rule over Hesperos was over, but at the same time Dominion invaded. Managed to defeat them near Sirmium and then sent an army by sea at Kobolos. Won that battle too, but then I had to face 3 Dominium elite armies including those nasty green gunners and flying monsters. I was defeated, obviously and now my campaign is pretty much over. Finances are killing me. I mostly have 5k or less gold each turn, so I had no way of building large armies.
Rushing an AI faction from the start I suspect no longer works if the AI gets some armies for free. Did that before, destroying the Dominium in the first 15 turns.