yo.
I know that uv sets can be advantage if you want to have high res maps on your character for example.
Lets say you want your characters face to have a high res map of 2048 x 2048, you can create a uv set just for the face. Then you can have all the uv's just for the face in the 0,1 texture space. If you had the face, and body in the 0,1 texutre space, you wouldnt be able to have the same res on your face because your shareing the 2048 map with the rest of the body.