Nearly finished with my Rome campaign, may even be over tonight (130/140 regions). Oft-mentioned AI and balance issues aside, something I've really liked is the diplomacy. Since the beginning I've fostered good relations with Macedon/Athens/Knossos, with Pergamon and Trapezos becoming my clients. There's a sort of "Greek Confederation" that controls Turkey and the near-East, and they've been very good to me. That's never happened in any of my TW games before. I've also used my money to fight proxy wars, since I didn't want to march troops out so far.
-Athens lost its capital about midway through, and instead of reclaiming it, took its remaining armies to Syria, conquered a region, and ended up becoming a significant force in the Middle East. I'm reminded of the humorous M2TW Edessa playthrough.
-Though I own the majority of the map, the "Greek Confederation" is a considerable power of its own, and it'd be quite a war if the AI coordinated itself properly. Definitely like the possibility.
-Considering the high number of unique units between them, I suspect Thrace and Dacia will be future DLC. Consider also that Dacia (Dahae?) can also form the Celtic Confederation.
-I've wreaked havoc against Parthia with my proxy wars. Funneling money to my allies in Armenia and the steppes has really worked. For all its problem, their AIs got stuff done.