I'm playing French, and i can say they truly don't have any destructive troop for wars/attacks
But their major advantage is that you can get rich real fast, even faster than nations with resources bonus or whatsoever . I stick to Copper I or Silver III, there i can find many players with uncollected Caravans, Farms which gives lots and lots of resources ( if we play smart, of course ) . Just drop some Ranged Calvary, spearmen, archers and i have got bunch of Resources . And the training time is really fast . You don't have to be online for like 24/24 . Just play regularly when you have free time .
For other countries, i'm not sure . But according to some of my friends, if you go to war. take Koreans , Their bonus Tactic can save many of your troops . Romans, despite having more troops, but if you can't save them, then they will still be useless .
Oh and i think Japan really sucks at war at later ages, since their defense will get slightly weaker and weaker as they advance .