I've visited the Porkies twice. February 2007 (as I mentioned above) and then again in I believe May of 2008. In May a buddy and I did a nice backpacking trip in which we checked out the majority of the ecosystem. One could backpack there for probably four or five days and get a great feel for the whole place.
indeed there's a lot to do in that park. i spent a week there a couple years ago, and only saw people near the really popular areas like lake of the clouds. other than that, it was rivers, trees and lake superior. beautiful area!