Would I upgrade to Win10 if it's free? What a remarkably low bar to set! And yet the answer is a resounding 'NO,' though with a few caveats. First, some feature might turn up that is either very useful or necessary; I don't know of anything yet, but we have a ways to go before the features get locked in stone, presumably with SP1. Second, I might put a Win10 image on a Win7 machine that needs a new coat of Windows anyway. Third, I will probably still have some Win7 machines in production when we reach the end of suppord in early 2020; if Win10 is no worse than it looks now, I might do a free upgrade, though I'd likely use the excuse buy a new machine if the upgrade cost over $50.
I grew out of needing the latest coolest thing a couple of decades ago, and I understand the cost of even a free upgrade in time, disruption, and training. If Micro$oft actually delivers an OS that adds real functionality that benefits my company, without stupid gratituitous changes that actually make it harder for my user base, I'll happily pay for it. If they just want to put clown makeup on a previously functional OS, I'm not biting.