I got an invitation to reserve Windows 10 upgrade, but I don’t think it was on an e-mail. I believe it was on an update notice type icon on my task bar. Does Microsoft do it that way?
That’s the way Microsoft does it for Windows 7 and 8 users.
Many FReepers have gotten this same notice and done the update. Majority of those posting have said that the update was seamless.
Just search Windows 10 on the search facility of FR and you will see many threads after July 29, 2015 where users talk about their experiences with Windows 10 updates.