I think the removal of the Start Button is a pretty interesting choice by Microsoft.
The Start Menu, which provides more-or-less equal real-estate to file browsers, programs and system settings, is becoming more and more obsolete. On my computer, I just want to click on a button and launch a program. I pin 8-10 programs to the Taskbar, and can't remember the last time I used the Start Menu for something other than changing settings or running a cmd script.
That said, there is a big disconnect between how consumers want Microsoft OS upgrade to work, which is change hands seamlessly in the background without a lot of grief to the user, and how Microsoft upgrades usually work, which is to throw a bunch of "new" ideas and formats at users in a new smorgasbord version of Windows, all two years too late to make a real difference...
Windows 8 seems to be MS's attempt to address a life or death question: What is the real purpose of the Windows operating system in a brand new hardware market dominated by mobile devices?
(sorry to hijack the thread btw, none of this is HTPC news...I heard a rumor, however, that in Windows 8 WMC will be completely replaced by JRiver Media Center 18)