I have used Office 365 Office 2016 for a week or so and it seems to work ok from a functionality perspective, still I will remove it from my client and use 2011 instead.
Why? Because it's insanely intrusive.
It connects to 5-6-7 different servers constantly, per app. The Office365ServiceV2 is also triggered by actions not related to Office.
My impression is that it basically has the function of spy-ware.
And if I block the connections (work off-line) it's lasts a few hours or max a day until functionality is shut down. Read-only mode.
Would be interesting if someone with Wireshark or similar checked what information it slurps from the clients, if that is possible, connections are encrypted.
It's an Office version of Win10 from a privacy perspective.