I've seen some of the extended gameplay (link below, skip to 7:50), you can do things like build your own settlements which travelers will come across and eventually inhabit, raiders will also come across your settlements and attack it, they've improved on modding weapons to the point you can turn one weapon into something else using the items you find lying around that in previous games were pointless. The game may have some short comings in reusing some assets but some of the changes will add replay value for months.
https://www.youtube.com/watch?v=xfb65f7Dfgc&list=WL&index=130







