I've been live testing it on a Dell netbook - specifically a Dell Inspiron Mini 1018, with a blazing fast Intel Atom 1.66ghz cpu, 2 gb of ram, 250gb hdd and video powered by the uber-awesome Intel GMA 3150 chipset. IOW, the vast majority of mobile phones kick this machines' butt.
And while I wouldn't use the term 'greased lightening', I will use the term 'entirely adequate', and 'above average' in other cases. Runs all the standard apps with no issues, YouTube videos run with no issue on both Firefox and IE, with no Adobe product involved, and, just for giggles, when it's not being used for anything serious, it runs a small population server for playing Everquest with a group of friends.
So given the hardware I put it on, I'd say a machine with a real processor and gpu would actually do pretty well, even with only the minimums.
I've never used a mobile 'windows' device. I'm not sure I've ever seen one, to be honest. So how Win10 will work on one of those is something I can't speculate on, other than if the optimize as well for mobile as they have for PC, then I can see it working just fine.