that is the question asked by Larian on their fessebook
(here is the post :
http://www.facebook.com/DivinityOriginalSin/posts/593839890642347)
In my opinion it should be an open world but that we have to discover through the scenario : I mean in D2, I was really frustrated when I discovered that you cannot go back to the first region once damian overtake it !!
I probably missed some quest or things the first time I played (not the second one^^).
Of course you should not be able to werhever you want as a level 1, you might have somes areas with stronger monster while you evolve in the story, but you should be able to go back in the places you went for example to complete a quest you put in standby for some reason or to see again the npc you interracted with...
Exploration has also always been an important part in larian games with a lot of hidden things so it is up to you to go in some places where the main story might not send you...
