Mitchell_A hit it right on...people are afraid of change. This was the case with 64 bit computing, which has been with us since the early 2000's (2002-2003), but it took the release of Windows 7 in 2009 (6 to 7 years after availability) to make it the "norm" for most users. The switch was really no big deal, only that some users has reported that 16 bit programs (from when....the Clinton era?) won't run on 64 bit computers.
It's going to be the same with Windows 8 at first. But those of us who took the dive from Day 1 (02/29/12) & have ran it daily since, knows the good that Windows 8 will offer. Lowered CPU usage, no more of that Aero crap (required for Vista/Windows 7), which was also a resource drinker.
Windows 8 computers will be "greener" ones, the OS will not be "power hungry", and the OS will run easily on the many cookie cutter, low spec computers that was put out with the release of Windows 7, which was also touted to be "greener", but nothing compared to Windows 8 CP & RP offers in power management.
Windows 8 computers will also startup faster than previous versions, taking into consideration all other factors are equal. For those with SSD's, there is an intentional delay, beginning with 8 RP, to allow the user to access boot options or get into the BIOS at startup. This was not the case with CP. Also, beginning with RP, the "NX" technology, a security feature, is being enforced, meaning that non-NX equipped computers won't see Windows 8 RP or Retail, unless a BIOS update can add it to the computer. NX has been with us for years, just not enforced.
Plus there are many Metro Apps that works quite well with Win 8 RP, something for most everyone. There's even a "Tom's Hardware" app listed, where many PC enthusiasts visits.
There is one big difference, that the lack of a Classic (or should I say "ancient") Start Menu. While this is no big deal to me, the Desktop can be accessed with one mouse click, & there's 3rd party software for those who "must have" a old timey Start Menu.
Start Menu 7 Once the OS becomes more popular, there will probably no doubt be other 3rd party Start Menu software offered.
One last thing, the Windows 8 user will have an AV/AM app built in right out of the box with Windows Defender, which is NOT to be confused with the versions of WD on Win 7, Vista & XP. Of course, the user can still disable WD & install the security software of his/her choosing.
Just a few thoughts to throw out there, after all, this is 2012, this will be the 1st version of Windows released in this decade. Come 01/13/2015 (less than 3 years away), Windows 7 users will be in the very same boat that XP users are in right now, less than a year after end of support for XP. Yes, the very same boat, just waiting to be kicked to the curb.
Not to mention that support for the current SP1 will expire on 04/09/13, w/o even a beta version of SP2 being rumored, let alone in place. SP2 for Windows 7 will have to be rushed to be in place by that date, or Windows 7's users won't have a supported SP.
Source for Windows 7 support lifecycle:
Microsoft Product Lifecycle Search Cat