I started playing Europa Barbarum the other day. Great detail (the Gestatae is rather gross, but detailed nonetheless), historical accuracy is pretty good, very fun, but rather buggy.
My favorite faction there is the Ptolemaic Greeks, well, I've had the most success with them. Though the Romans have some awesome units later on, but those Heavy Samnite Mercenaries are great, along with the regulars.
EB is quite different from RTR. If you like stability in your game stick with RTR.
BE FOREWARNED, IF YOU UPGRADE THE VERSION OF THE GAME YOU'RE PLAYING, YOU CANNOT LOAD YOUR SAVEGAMES!!!!!! (In EB that is)
I found that out the hard way, I can no longer play as my greatly powerful Ptolemaics, the massacre of "Sets Army of Mesopatamia" can not be avenged....
Worthless Seleucids, my men fought bravely, but the overwhelming number of Seleucid barbarians overwhelmed them, and they wouldn't settle for my army retreating, they had to annihilate it.