After some time with Windows 10 Pro x64 on my machine I'd have to say I really enjoy the experience. Things work faster and there doesn't seem to be any issues with anything. Hell, even the games that weren't working in Windows 8.1 are now working in Windows 10, go figure (Yes I'm looking at you Fallout 3). Personally, I don't honestly see any reason to not upgrade to Windows 10. Anyone clutching onto Windows 7 because they're weary of a new OS, while I don't blame you, it's time to move on. Windows 7 had it's run, it was great, but honestly... Windows 10 blows the doors off of Windows 7. Just make sure you turn off all that spyware crap they put in the core of the OS, and make sure to un-install cortana. Aside from that, you're golden.