Windows 8 Sales Well Below Projections, Plenty of Blame to Go Around | Windows 8 content from Paul Thurrott's SuperSite for Windows

Check this page for Paul Thurrott's detailed list of eight market factors that could be stalling Windows 8

"The net effect of all this stuff, I think, contributes to a wait-and-see approach with Windows 8. And that is exactly the opposite of what Microsoft and even the broader industry should want at this time. In this way, the Windows 8 launch is much like that of Vista, where a nagging (and in that case, tech blogger-led) cabal of disappointed voices dominated the discussion at launch and torpedoed the product before it had a chance. Windows 8 is no Vista, in many ways. Until it is.
All of this was avoidable."

With all due respect to Paul Thurrott, I'm not sure it was all avoidable, if PC market saturation, contentment with Windows 7 PCs, and a widespread shift to tablets and smartphones together represent the ultimate Windows 8 challenge.

Also see Forrester finds mixed prospects for Windows 8 in the enterprise (ZDNet)

Windows 8 Sales Well Below Projections, Plenty of Blame to Go Around | Windows 8 content from Paul Thurrott's SuperSite for Windows