I bought the version for 5 Users (Macs/PCs) with each 1 TB OneDrive on Amazon too for 69€/year. That's the same price as a single user license if you buy it directly from Microsoft and 30€ cheaper than the 5 User version.
Edit: You also can choose to install the 2011 version until September 22nd 2016, if the new version has still too many issues or you just don't like it.
The Amazon version works exactly the same as the Microsoft version. You just have to put in the key in your Office365 account. The price for a little box with the key card or just getting it digital is the same at Amazon.
Sometimes you also get a 10€ gift card for the Microsoft App Store with it. I got that last year, but had no use for it. 😉