After updating my little tablet to Windows 10 (previously Windows 8.1) I have to say that it’s actually a step backwards.
For pure touch devices like tablets, 8.x was really good. The swipe in charms bar and Start screen were really intuitive and useful. Windows 10’s setup is sortof a bad remerge with the pure-Desktop design of 7.
Aside from that though, it oddly decided that I no longer had a touchscreen. On a tablet, that’s bad. It would still register touches, but wouldn’t bring up the touch keyboard when tapping on a text field. This is most annoying when you are trying to type in your password and have to use Ease of Access’s On Screen Keyboard or OSK.
I recommend sticking with 8.x if you are using a tablet. On a regular PC, 10 seems to be working fine.