I already am. Windows NT 10.x is at build 10130—it goes gold on 29 July.
(Unlimited Internet plan F/T/W: The DVDs are ~3GB, updated every 8.2 days, and may accelerate as the release date gets closer)
So far, it’s quite good. Anyone using Windows 7 presently will not feel too far out of place in Windows 10.
I'll give it a few months for the bugs to get worked out, then upgrade. Sounds like the upgrade is free, so the price is right.