On busy roads where you are in a queue of traffic, I tend to turn it off as it can be selective on what it 'lights up' in front of you. I have found a particular problem with white cars(probably reflection), but you come up behind and full beam comes on - seems particularly bad with white X5's! Also where someone has a light out, it thinks the car is a bike and again lights up.
I do use the Matrix system, just leave it on auto and let it go for it but it isn't as clever as it makes out on the Audi website. There are many occasions where, following a vehicle round a corner, the matrix will shift to another LED (keeping the vehicle in front in the dark) and then when we straighten out it takes a little time (about 1 second) for the matrix dark spot to return to the centre meaning the car infront gets a brief blinding