The second playable faction from Total War: Rome 2 (after Romans, of course) has been detailed: the North African state of Carthage.
As explained in their page on the official wiki, Carthage is “an expansionist trading state with a small indigenous population,” whose armies consist mostly of mercenary units.
“The core of its land forces, however, are elite Carthaginian citizens known as the Sacred Band and mighty war elephants from the forests of North Africa. Accomplished seamen, their ships are fast and manoeuvrable, with good ramming and missile capabilities.”
“As a playable faction, Carthage benefits from its mastery of the waves and its heritage as a great trading nation. As a democracy, it also enjoys an improved level of population happiness. The player also has the choice to play as one of three major political powers, each of which confers further military, economic and cultural benefits.”