I upgraded three computers to Windows 10 a few months ago. One each from Vista, 7, and 8. All three had showstopper problems. One would never again resume from

I upgraded three computers to Windows 10 a few months ago. One each from Vista, 7, and 8. All three had showstopper problems. One would never again resume from sleep and had to be downgraded (HP laptop). One encountered a permanent boot error on the second boot into 10, and had to be completely wiped to make it work (Lenovo desktop, only a year old). And the third required purchase of a new graphics card, because acceleration which worked in Win7 does not work in Win10 if you have older Intel integrated graphics. These free upgrades cost me about 15 hours of lost time, $80 in hardware, and a lot of goodwill. Or I guess I should say, two upgrades, since one had to be undone.