This "free" upgrade has been going for years, it is not new news. What I question is what will M$ do once W7 expires? Will they still allow these "free" upgrades or will the ax come down on those who waited too long?
The reason why a lot of people say that when you buy or acquire a legal key that the installation is legal is because Windows 10 is completely free to download install and use right from Microsoft. It`s the legal key that puts the software and license together and makes your copy of Windows fully legal to use on your machine just so you understand so if your using a legal key then yes your software installation on your machine is completely legal! That being said you can still download, install and use windows 10 without being activated and its still legal to try and will continue to function as a full fledged operating system just that unless it is activated with a LEGAL key some functions of the operating system that's really more like eye candy then anything else won`t be enabled. When you purchase windows 10 your not paying for the software per say your paying for the key or license agreement. The software is free...