Michael Mace, in “Fear and Loathing and Windows 8”:

The most important message I want you to understand is this: Windows 8 is not Windows.  Although Microsoft calls it Windows, and a lot of Windows code may still be present under the hood, Windows 8 is a completely new operating system in every way that matters to users.  It looks different, it works differently, and it forces you to re-learn much of what you know today about computers.  From a user perspective, Microsoft Windows is being killed this fall and replaced by an entirely new OS that has a Windows 7 emulator tacked onto it.

Long, but a must-read.