Windows 10 boots faster, works faster, and seems much more robust than either Windows 7 or Windows 8/8.1. I haven't had any problems with drivers or programs that run on Windows 8/8.1, although all of those old Metro apps are destined for the bit bucket. Clearly, the new Windows Universal apps hold great promise, but they aren't there yet.
Windows 10's signature new feature, of course, is the Start menu. The new Start menu combines a severely stripped-down version of the Windows 7 Start menu with a mouse-friendly field of Windows 8-like tiles.
If you're coming from Windows 7, the left side of the Start menu will look vaguely familiar, but the Windows 10 version is much less malleable than the Windows 7 version. In Windows 10, you can't create custom menu items, build cascading menus, or pin your own apps, files, or locations to the Start menu. You only get a fixed set of 10 apps that can be pinned to the bottom-left side of the menu, along with File Explorer and Settings, which can be removed.
If you're coming from Windows 8/8.1 and using a mouse, the field of tiles should feel quite similar to the Metro Start screen, with the new ability to run the tiled apps in resizable windows on the desktop. Methods for grouping and manipulating the tiles are different in Windows 10, but cover much the same ground as those in Windows 8. In Windows 10, tiles are grouped rigidly in three- or four-wide groups. You can change the number of groups that are visible by widening or narrowing the Start menu. That's considerably more restrictive than Windows 8/8.1.
If you're coming from Windows 8.1 with a mostly tablet mindset, the new Tablet mode in Windows 10 has much of the ease-of-use benefits of touch Windows 8.1, such as spread-out tiles and the Start options hidden under a hamburger icon, with a few minor annoyances. For example, you can't turn off the taskbar at the bottom of the screen, no matter which app is running. You're also stuck with the rigid organization of tiles into three- or four-wide groups.
Charms? Gone. Left-side task switching? Gone. Good riddance.
Other ease-of-use improvements abound. For example, Microsoft seems to have finally perfected in-place upgrades. Cortana is starting to become a viable "assistant," and if you're willing to let Microsoft look at your activities, the potential for Cortana help extends into every interaction you have with Windows.
One widely touted ease-of-use benefit of Windows 10 -- the ability to run nearly identical Universal applications on phones, tablets, PCs, Xbox, and all Windows 10-branded devices -- remains elusive. Whether Microsoft will be able to deliver a WinRT API that works on all those devices, and whether app developers will take advantage of the API, is still very much up in the air -- particularly given Microsoft's recent retrenchment on Windows Phone.
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