Gameplanet - Five features that changed gaming.
While there is a definitely an argument to be made for open level versus linear level design (after all, it's much easier to give focused experience in a linear game), if it’s done right, an open world game can give you an experience like few others. Fallout 3 and Grand Theft Auto IV are but two examples. Those are large worlds filled with so much to see and do that not only will they keep you busy for hours, but you’ll enjoy most of that time too. And best of all, it’s completely your own experience. In a linear game you can share a great moment with your friends, as you all experienced it. However, in a sandbox world you will all have had a different experience with the game.