I upgraded my Win 8.1 laptop to Win 10 and have had no problems so far. It is easy to change privacy settings so that nothing is tracked or sent to Microsoft. To shut off automatic updates on a wifi connection, just set that connection to "Managed". Don't use Cortina as it will turn privacy settings back. It is running much more evenly than with 8.1 did and I no longer get the pita side bar opening if the mouse goes over to the right side of the screen. The upgrade install was smooth and easy and none of my installed software was touched. If you experience slower boot, then go into privacy settings and turn everything off - because this is what slows boot time on Win 10 - and you don't want anything being sent out anyway.