Ok, Pila work fine for me, when attacking the unit stops, throw, then charges into a now disorganised and shaken enemy unit. When defending stand them still and hit fire at will and they will get some off, unless charged by cavalry or other super fast units, but thats fair. When charged by infantry it's rare they don't get a shot off.

But the javlin units, light auxillia, velite's and so on, they are much more difficult to use. Stand them infront of you line with skirmish off and they will get a few shots thanks to the greater range, but they will get hit full force by the enemy and break easily, demoralising the rest of your army. Position them behind your battle line, and everyone gets a javlin in the back of the head.

While I've gopt used to the kill speed and infantry speed, that means that if you try and move your javlins around to the flank or rear, by the time they get there the battle has been decided. if fighting cavalry quite often the cavalry has charged straight through the enemy unit and turned around, meaning you would be throwing javlins at your own troops again.

The best use I have made of them is by putting them infront of the army, any archer units to the side, with skirmish on, let them have a shot or three, then run and the MOMENT they start to run take fire at will off and ignore them unless sorely pressed for troops.