The software giant has been slowly unveiling all the new features of Windows 10, and beta users have been testing it for months now. Microsoft has brought back the Start menu, introduced a new browser (Microsoft Edge), introduced the Cortana voice-activated personal assistant, Windows Hello for biometric security, Continuum to better sync your Windows 10 phone to your desktop and ensured that all your existing apps work with the new operating system.
Perhaps most importantly, Microsoft has finally created an ecosystem that can thrive on your Xbox console, your phone, your PC, your tablet and even on your Raspberry Pi. Until now, Microsoft had become pretty fractured but Microsoft seems to be ready to truly play ball.
For more info on upgrading, here is the official source.