Heres what I encountered when I, as a first time ever user, was directed to a document that lived in Office 365 World:
Holy crap, Microsoft! I just wanted to read the document a colleague at another (much larger, older, and traditional) company had sent me.
When this happens with Google, well, most of us have a Google account, so the link would redirect to this:
Pretty easy, and even if you dont have a Google account, you see this:
Better, but still not great.
So I wondered what its like at, say, DropBox.
Ah, yes. Thats the ticket.
Microsoft, you have a lot to learn about living on the web.