After installing fast ring 1710 b8613.1000 when I go to File|Open, then select Sharepoint for our work Office 365 site, I just get a list of recently used folders. I much MUCH MUCH preferred the list of all of the Groups/Teams and Sharepoint sites I have access to. The MRU list for files in RECENT is fine, but folders in Sharepoint is useless to me. With folders, you can never create a new file and save directly to the group. You always have to save locally, then move the file, then reopen it.
Of course, a lot of our users forget the 2nd part so they just leave it on their desktop. :-( Hoping the group feature rolls out wide so they can create a new file and save to a Team in one step.
I posted this in Excel because that is what I use most, but applies to Word and PowerPoint as well.