I like this product because it can make snacks on-the-go more successful. M often gets too distracted when we're not eating at home, and eats very little for snack, only to be hungry soon thereafter. I find that if I bring milk with snacks on-the-go, she is more likely to drink it, giving her some protein, fat and carb to give the snack a little more staying power. Normally I pack water or diluted juice in a thermos, and I'm not thrilled about the waste with the boxes, but I don't like putting milk in thermoses. (Have you ever discovered a thermos of curdled milk in your car? Usually the smell clues you in first...)
Also, these guys are ultra-pasteurized, so you don't have to store them all in your fridge. Very convenient.
There is a chocolate milk option.
For older kids who may skip breakfast, a milk box and some trail mix or cereal bar on the way to school is better than nothing!