As I said, there's a little bit for everyone, so it would seem. There's new Roman commanders (including the game's namesake, Caesar) and infantry. Or you can head to Spain and see the various command units and infantry pieces there. Perhaps a trip up to Germany, if you have the Gaul. Perhaps that's a bit cold for your liking. Then you can head down to Numidia and bless the rains down in Africa. It's really all up to you.
Roman Source
Germany Source
Numidia Source
Spanish Source
