I've upgraded a few machines in the office and it went so well I upgraded my home PC last night. My initial review of W10: Awesome!
The upgrade process is really simple and easy. I've now done three machines and had almost no issues at all. The OS is faster that W7 and the interface is more user friendly. I believe non-tech folks will enjoy it while it still retains enough to make us professional techs happy.
The biggest hiccup I ran into was on my home PC. My Netgear A6210 wireless adapter wouldn't work. I had to completely uninstall it ... go through the registery and delete all mention of it ... let Windows install a basic driver which allowed it to connect on 2.4. Then I was able to install the official .30 Netgear driver and connect on the 5G.
The biggest hiccup at work is that the Sonicwall VPN software doesn't like W10 at all. I be looking for an update or looking for another VPN solution.
If games work on W7 they should work on W10. Last night I got ME 1, ME 2, ME 3, Skyrim, SWTOR, Witcher 3, Space Engineers, Civ 5, Dragon Age Inquistion ... all ran perfectly after the upgrade, many which include mods.
Microsoft has apparently gotten W10 right. It looks great, it runs great, and the upgrade process is very simple. You may run into a few issues with specific peripherals or software so be sure to test anything critical before. Oh, and as always ... back up your data first (though I had no issue with losing data).