Quick Access to Favorites or Recent Folders, 3D Touch
It would be nice to have a favorites or recent folders option. Not sure if this should sync in any way to recently visited folders from all devices but end goal would be to have a quick way to access some sub folders instead of drilling down from the top directory every time. Maybe a swipe left or right on the main screen to get to folders or files you recently or frequently access and tagged/marked them as such.
For those iOS devices that support the additional 3D touch functionality you could also have favorites listed there. Press and hold for a quick pop up top 3-4 directories and open OneDrive right to it.