I have had a chance to work on Windows from its Windows 3.11 for workgroups, back in 1995, all the way to the current Windows 7 and the upcoming Windows 8 as well. In my experience no previous Windows version was this eagerly awaited and extensively discussed as is happening for Windows 8.
There have been hitches in between like the Windows Millennium edition and Windows Vista, and the versions succeeding them did get good attention, but those are still easily eclipsed in front of news Windows 8 is making. Industry and media is abuzz with speculation on success or failure of Windows 8 and is the RTM version really ready for worldwide launch or not.
In my view Windows 8 is a significant milestone in two key aspects (but which are related on one another). One, MS is the first time moving away from the PC based model to imbibe mobility in their platform. There is a recognition that PC sales are being impacted by tablet sales and hence Windows 8 is really designed keeping tablet and touch interface in mind. The related second aspect is breaking away from WinTel monopoly and including Windows On ARM (WOA). Any platform targeting tablets cannot keep distance from ARM, as most of such devices are powered by ARM chips, mainly due to their power friendliness.
Intel x86-64 bit architecture is different from ARM and hence application written on one cannot run on another without at least a recompilation at the minimum. MS .NET's platform agnostic MSIL compiled assemblies that are JIT compiled to the native processor at runtime has helped shield the developers from this recompilation issues. The new Windows runtime (WinRT), the new platform for creating Windows Store apps, leverages similar capabilities to ease developer's work. Applications built using XAML and C#/VB.NET targeting WinRT compile into MSIL and are compiled into native code when deployed on the Windows Store providing for both x86 and ARM versions. Applications built using C/C++ targeting WinRT can be specifically compiled to target ARM chips, via a configuration change in Visual Studio 2012.
Given that Windows 8 is targeted towards tablets and will launch worldwide on 26th October along with the MS Surface tablets, another important aspect is the store's readiness. The tablet and smart phone world is thriving on applications in the store that consumers directly download on their devices. The Android market place is currently leading with maximum applications. It is win win for developers and consumers. MS realizes that success of Windows 8 at launch will be highly influenced by the number of applications in the Windows Store and is hence aggressively trying to get more and more apps in the store. They have a mere 2000+ apps as yet, but events like Guinness World Record holding App Fests are bringing in more and more developers on board, which will help push more apps to the store shortly.
With the significant user experience shift with Windows Store Apps on Windows 8 and MS's not successful Phone 7 storyline, the speculations on success or failure are bound to exist. Enriching the Windows Store with apps is a mammoth task and nothing short of a miracle can probably get MS the numbers they may want at launch time. While many keep comparing # apps on the MS, Android and iOS stores, I am not sure if an average daily user really uses more than 100 different apps from the store? (read here and here)
Will Windows 8 eventually succeed or not is anybody's guess, but with my personal liking for MS products and looking at the strong history of success of Windows OS, i would be inclined to hazard that Windows 8 will succeed, albeit a bit slowly.
I would be glad to hear your views and discuss this further.