Microsoft admits Windows 10 preview has a keylogger
Microsoft has admitted that the new Windows 10 operating system tracks keystrokes and examines audio input. The new operating system, currently a free download for users with Windows 7 and Windows 8 licences, not only tracks how long it takes to open different types of files, the make and model of device you're using, but it's also logging keystrokes and collecting voice recordings. Microsoft will not delete data already collected from Windows 10 users.
I could go on and on, but these are real world examples I've seen that completely break workflow with the abrupt shift to full screen apps. On a tablet it's not so bad since desktop mode is the red-headed stepchild on such a device; however, on a full desktop or even non-touch laptop with traditional keyboard and mouse, it's anything from annoying to frustrating to "screw this bullshit" level, depending on the user.