At first I didn't think the Gauls were any good. After thrashing them with the Juili. But they are a pretty cool faction to play with. Their Forester Warbands are amazing and one of my favorite units in the game. Barbarian Noble calvary and chosen swordsmen are also pretty solid units to fill out the rest of the army. Their pretty easy to play with in campaign. (I played medium campaign and hard battles) The Germans and Spanish can easily be cut down with Foresters and Noble Calvary. The Britians can be a little tricky with the chariots, but foresters with flaming arrows can be affective. The Romans can also be tough, but if you strike before Marius you can overpower them. One huge downside that ticks me off is that they can't construct stone walls. Another disadvantage is no artillery, so that means no assualts or massive artillery bombardments. Overall the Gauls are great in the begining and towards the middle of the game, but Marius and the Romans can overwell them with superior units later on in the game.