I upgraded to Win 8.1 last night. My goodness, what a process for a dot release! My Windows laptop is admittedly a bit antiquated, an HP Intel Centrino2 2.13GHz Core2 Duo system with an HDD, but I think a two hour plus upgrade process is more than one would reasonably expect. Most of MSFT's work appears be in an entirely new security and trust architecture, which also changes the entire sign-on process; it is much more Apple OS-X-like. As for the rest of the 8.1 upgrade, the addition of a Start button, well, there's something like Start button functionality that's been added. I don't like it as much, because rather than a pop-up of the menu hierarchy on the current screen, as in Win 7, it takes you to a dedicated application screen, which I assume was driven by the needs of the Surface product line. So far I haven't noticed any other significant differences between 8.0 and 8.1, so it does leave me wondering why a new security model was slipped in under the guise of a rushed-to-market dot release.
Perhaps I am also beginning to understand Microsoft's strategy. The Surface is the future for them. The PC as we know it is considered a legacy product line. For people who must still live in their PCs, so to speak, for business reasons, I'm thinking Win 7 can be considered in reality an end-of-life software release.