I'll be sticking with Windows 7. That is an OS designed to be operated optimally with precision input devices. Which means that screen space is utilized efficiently throughout the interactive experience. Whether it is the resizable windows and their minimalist menu tree toolbars, or the compact icon-laden desktop and windows workspaces, or the feature dense configuration and interactive menus from general programs. Such UI efficiency is also most immediately evident in the excellent Start Menu. This one button centralizes all the functionality of your OS into one location - all neatly organized and easily accessible. Your personal files, pinned and most frequently used items, all program tree, universal search, computer explorer, control panel, devices, network, help and shutdown. Any one of those functions can be easily launched WITHOUT obscuring your multiple windows and desktop workspace. Productivity, research, entertainment, communication or a multitasking combination thereof, whatever task I want to accomplish on my computing device I do not want the UI system to get in the way. It is this unobtrusive and non-constrained nature of the Start Menu-Windows-Desktop-Icons-Pointer UI system of Windows 7 which I prefer.
Metroblox 8 has a full screen interface that is archaic and constraining in capability to both users and developers by comparison. Even the 'live' tile feature is not new, desktop gadgets/widgets of Windows 7 and XP provide identical functionality without being intrusive. I certainly hope that this mess of a UI system is discarded entirely or made optional in the next Windows.
I find it ridiculous that anyone would dismiss the Start button menu as irrelevant. Such people do not make full use of the functionality it provides so they obviously have no need for it.