We've had it run 24x7 with reboots due to automatic updates and power outages. It's a dedicate little netbook collecting process data. So if the OS was unstable, I'd think it would show.
I have my window 7 for a little over one year, during the year of uses, there always a little problem here and there, but for certain time after, the problem will gone and soon a new problem come up.
Each time when problem come up, it always take me a long search to trying to get the problem fix and as always, not a chance but wait the problem gone away by itself. this could be month or two, etc.
Why this will happen, when my old system with XP, not that many problem that I face as window 7.
So, with window 8 come up, I do have to wait and see how other users comments.