I had Windows10 for about 6 weeks, about 3 weeks after it was released.
It upgraded fine.
The laptop then started to have the odd error (week 1).
The laptop then became unstable, the odd crash, but very slow (week 2).
Video stopped working, and couldn't find any solutions (that worked) online, their preferred option was a reinstall.
After several attempts to get video working it was crashing every time I used it (week 4).
Tried in vain to get solutions for microsoft who are utterly usless.
They suggested I did a reinstall, there's two options, 1 that retains your data, one that does a clean reinstall (week 5), I opted for the reinstall that retains my data.
It seemed to go OK, then after several hours (18 I think) it just never came back to the Win10 screen, well that's not quite true, it just never came back to a situation that I could log back in (week 6).
My only option at that point was to do a factory reset back to Win 7.
I now have a happily running (super clean) version of Win7 on my laptop, (other than it keeps asking me to upgrade to Win10), luckily I'd got everything backed up so didn't lose anything. I spoke to microsoft who confirmed my laptop was compatible, and told me that I was one of very few who'd any problems. I spoke to HP, who told me that they don't recommend anyone with a Win7 laptop upgrade to Win10.
I'll be taking HP's advice.