I believe they've explicitly said in one of their official videos that it is not free roam (like GTA), but that it is somewhat sandbox-like. Like you're confined to an area, you have a problem to solve, but you've got enough sandbox freedom to decide from several different ways to approach it tactically. If you really want to know, watch all their official videos, it won't take that long.
I kinda wish starhawk would have had a free roam SP. It would have been awesome!!! But then again it's mp wouldn't be as good since free roam games take a while to develop.
Locking this thread because it's ooooold! -space_cape!!