In the first 24 hours, Windows 10 has landed on over 14 million devices according to Microsoft. That would easily make Windows 10 one of the quickest adopted versions of Windows with reviews of the new flagship OS from Redmond being generally positive. I personally have installed it on both my primary PC and tablet (Toshiba Encore 2) and both have performed flawlessly. Indeed I would suggest the Tablet mode is a massively improved experience over Windows 8.1 for my Toshiba tablet.
Microsoft hosted launch events globally, mostly in their retail outlets here in the United States, and all indications are those were well attended.