her registry was messed up and the upgrade imported her problem to 10 so I clean installed 10 wiping out her drive and she's very happy with it.
I think a lot of the heat people are giving it about being "buggy" boils down to exactly this. They did an upgrade install on their four+ year old Windows 7 or 8 system with all sorts of orphaned garbage in their registry that was mostly benign but materialized into actual issues after the upgrade. Then they blame Windows 10 and call it a day, when the reality is they were just waaaaay overdue for a clean install and upgrade installs have a long history of ending poorly on junked-up systems.
The MS flub here was not letting us use a website to activate our old Win7/Win8 keys so we can do a clean install straight off. This upgrade, activate, *then* reinstall clean thing is a headache.
That being said, I had a new machine that I did a fresh install of Win8.1 and immediately upgraded to Win10 on release day and I'm more than happy with it. My only issue is some obscure thing where apparently they removed a video codec they used to supply with Win7/Win8 and certain videos come out green and janky in MPC. They work fine in VLC though, and I'm sure the popular codec packs will start rolling up the missing codec soon enough.
