You can't activate Windows 10 with a 7/8/8.1 key. You have to upgrade and then clean install. Which is stupid I will admit.
But are you basing the "bugginess" of Windows 10 off of other people's experiences or yours? Most of the time people just parrot what other Windows 7 circlejerkers say and jump on the hate bandwagon.
(Which is what happened with 8, and 8.1 as well.)
Yea, already knew all of that since before end users could download it.
I make my own judgement. User information is used to test their bazaar and sometime utterly retarded problems. I admit a lot of them are the user.