I keep reading about the great success of Windows 10 - 14 million downloads as I write this. That absolutely would be an impressive number if it were Mac OS X, but 14 million might be only around 5% of Windows users. I say "might be" because although Windows users are estimated at 250 million, that figure could include many machines that technically still exist but have effectively been abandoned in favor of tablets. So the download percentage may in fact be higher, but I still don't think it is high.
Then again, it is early days. The advertising push has barely begun. Certainly many more will explore Windows 10. However, all those technically abandoned machines will not and neither will many Win 7 users who saw the horror of Windows 8 and mistrust Windows 10 because of that.
I'd also guess that the vast majority of extant Windows machines are installed in business environments and most of those may not upgrade for some time - or perhaps not at all. As of July 2015, NetMarketShare.com says 60% of desktop PC's are running Windows 7, and plainly didn't upgrade to Windows 8. Why should we think they'll jump at Windows 10?
Finally, there's no money involved - yet. Unlike Apple, Microsoft has no intention of making this free forever. Those who wait too long will have to pay if they want to upgrade. That's the real test of success: will they pay?
So is 14 million free upgrades something to celebrate or should Satya Nadella be worried sick?