Useless, in the original fallout you could put items in the bag, and the game couldn't detect the item (for quests and stuff, where you're giving someone something).
You can put stuff into it, theoretically it could make your inventory look less cluttered but it's all too much hassle for my liking. Alternatively you could locate the hidden scissors and cut a face out and stick it on your head. Then scare the bejesus out of little thieving children. Wait, they forgot to add the scissors! Damn. A missed opportunity.
