DON'T DO IT.
I mostly liked Win8.
I see a couple of things in 10 that are probably improvements.
However the update has @ss-effed my display.
After a couple hours searching, my video card is apparentlt too old. Nvidia has win10 drivers, but my card only goes to 8.1
In the process of rolling back.
http://www.cnet.com/how-to/windows-10-how-to-roll-back/ I'll see how well that works.