I am seeing a bunch of people complaining about the added W10 icon in their System Tray/Notification areas. And sadly, I am seeing some recommend to uninstall the update that put it there. I think that is a mistake and I am recommending for those who don't want it in their tray to just change the settings for the icon in their Customize icons menu to "Only show notifications". Then it will remain hidden until something new is announced.
I am also recommending folks reserve their copies. This will give MS a better idea of how many will be upgrading and it will (if they take advantage of the info) allow MS to do some load leveling when the update does go out.
And finally, I am recommending folks ensure they keep Windows fully updated to ensure the best chance the upgrade to W10 goes smoothly.