THE GOOD Windows 10 bridges the gap between PCs and tablets without alienating anyone. The new OS combines the best bits of old and new Windows features into a cohesive package, while correcting nearly all of the missteps of Windows 8. The upgrade process is mostly painless, and free for most Windows 7 and 8 users.
THE BAD Many of the new features will be lost on those who don't care about touch. Automatic, forced updates could spell trouble later on. Cortana's features are better suited for smartphones.
THE BOTTOM LINE Windows 10 delivers a refined, vastly improved vision for the future of computing with an operating system that's equally at home on tablets and traditional PCs -- and it's a free upgrade for most users.
Microsoft Windows 10 review - CNET