I've played as Byzantium and it is a lot of fun. Byzantium is fun to play because you have all the units for all the parts of an army you could want but they're so sub-par I use them exclusively for the things they're good at. Byzantine lancers melt really fast after a charge so I use the missle troops to fire my missles, use my swords specifically against enemy infantry spears specifically cavalry, archers as normal missle units, etc. Byzantium's exceptional units are the Byzantine Guard archers, Vardarotoi, and Latinkon both types. Dismopunted lancers are the best swords they have and they're ok.. Kataphraktoi aren't all bad, Byzantine cavalry is a decent unit, and the Byzantine Infantry does come from a city remember. Most catholic nations can't build swords in cities, the exception is Iberia and Italy. Overall it's a very delicate balancing act and everything must be done just right.

I turtle to so I get to have the fun of defending some fort on the edge of the empire somewheres to deversify my game. Fort's are a great way to get the most fun out of a Byzantine game in my opinion. And you know they have to carry on the tradition's of Rome.. I love trying to leave the small forces I leave there to victory though it's challenging. Of course I try to bring up some cavalry as reinforcements. Makes for some interesting campaign battles though. A lot of Byzantine units are said to have been used in fort defense in game to so it just feels authentic.