And a big GOTCHA it is too.
Now I'll admit that for a few the "free" Windows 10 may work out ok, but for those more active with their computer innards or software, the "Free" upgrade may become a desperate "GOTA BUY it RIGHT NOW NO MATTER WHAT IT COSTS" situation.
The problem?
Over the years I've had to reactivate Windows 7 Professional a number of times.
As when cloning it from an old hard drive to a SSD.
As when replacing the motherboard.
As when ...
And whenever I did it wasn't any problem at all.
But that fact is that I've reactivated Win 7 Pro four, maybe five, times. Not a problem.
From Microsoft - Q: What happens if I change the hardware configuration of my Windows 10 device?
A quick glance at the answer might mislead you.
Part 1 -"A: If the hardware configuration of your Windows 10 device changes significantly (e.g. motherboard change) Windows may require re-activation on the device. This is the same experience as prior versions of Windows (e.g. Windows 7 and Windows 8.1)."
Fair enough, no problem there.
BUT!
Part 2 -"The free upgrade offer will not apply to activation of Windows 10 in such scenarios where hardware changes reset Activation. "
I think that "free" may cost too much in my case.