I think the reported 40 hours plus length of this game is really starting to make sense now with this trailer.
I mean they've confirmed that the game covers the full nine realms and the first game primarily game us Midgard and in this trailer we saw Kratos look down on Svartalfheim where he meets the Dwarves and that alone looks to be the same if not bigger than the original game.
Of course, it doesn't mean that we'll get full access to every one of the nine realms because that could well be too big. When I finished the first game I would have happily had more to play and explore but obviously it doesn't mean that over 40 hours is going to be better than the length of the last game because it's all about the quality of what you do with that space.
I do feel that it will be good to have more to explore in this game though with more hidden areas to find and maybe even extra bosses with unique unlocks. I don't always feel that a more open world is best and I'm sort of hoping for a far more linear and dark game with Wolverine that we had with Spider-Man. I don't fel that needs to have an open world but if it must, I really hope that it's not New York.