[sundvor]

Just came across how you get "signed up" for the upgrade - see the main screenshot here:

http://www.pcworld.com/article/3078663/windows/microsoft-den...

That's definitely a textbook case of a dark pattern.

[Mithaldu]

I believe the screenshot is what you get when you did not cancel the scheduled upgrade and the process starts in earnest.

Note the very nice video in there.