Very happy with Windows 10 so far. I've only been using it for a couple hours now, but I haven't had any problems and it seems to run better than 8.1 was. Plus damn Cortana is a nice implementation. I've been loving Google Now on my phone, so being able to have a (slightly worse) version for my computer is nice. I just wish they'd allow Cortana to integrate with Firefox/Chrome as well as she does Edge (which is a step up from IE, but still not very good). I just wish she was half as good at contextual questions/commands as Google Now is. If I'm not super specific about some things, she'll just search what I said instead of figuring out what I meant like Google Now does.
But still, step up from Windows 8.1. I like the look, too.