I've used windows 8.1 myself, and I have to say it's really awesome on tablets. You can run any windows based application on your tablet, this gives it a lot more flexibility over iOs because now i can use third party software that hasn't gone through a pre-approval process. Additionally, the charms menu is actually useful on touch devices. On the desktop it's really not good at all, it boots pretty damn fast, the applications load quickly- But other than that it's the Metro UI that really gets in the way and reduces the overall "Greatness" of windows 8 on desktops.