I like both.... but the problem with open ones are that if you don't have 100 hrs to put in you don't really know what side quest are woth doing or even important in terms of character stats devlopement.... now FFXIII is way too linear... I mean come on even if you loved it don't tell you didn't feel riped off a litle at that price tag... I expect something more evolved... in terms of gameplay..... I think the one that coined it are bethesda in mass effect 2.... even though we could have used more side quest and a main story more like the first one.... I felt like I could do everything without wasting time like in fallout, and at the same time I could go linear and not miss much.....
I think for open worlds like elder scroll and fallout they should have an option where you can tell how many hours you want to put in and it cuts off the less important quest in relation to the box you ticked.... a bit like the level of difficulty but for time.....