It's really awesome, I have 0 problems and no driver issue or anything. The interface is what Win 8 should have been and I am glad I went ahead with the upgrade. The addition of Cortana is awesome even tho you have to be set to US location to use her till they add more regions.
If you didn't get your upgrade notification yet, here is how to force it.
*** One really important thing if you upgrade tho, go to your Windows Updates, then to "choose how updates are delivered" and set your updates to local network only. By default your PC is set to send updates to all other PC over the internet....
*** If you are on Wi-Fi, also read how to deactivate "Wi-Fi Sense"