OK, I decided to take the plunge. Unfortunately, my upgrade did not go as smooth as I hoped, but here is a summary of things to look out for from my experience. (Please, no "Windows sucks" replies, this is meant to be informative for those who *might* plan on upgrading / experimenting [if at their own peril].)

First off, I upgraded from Windows 7 Ultimate to Windows 10 Pro using the "Reservation icon" and the Windows Update mechanism. Update downloaded, never installed. Make sure you go into your Windows Update settings and choose to let Windows install updates automatically. Ultimately, after changing this and rebooting, I went to check for updates and then forced the Windows update from an Administrative command prompt using "wuauclt.exe /updatenow".

Issues and resolutions:

a) If you have any VPN (I had the Cisco VPN client installed) in either Windows 7 or Windows 8.1, UNINSTALL IT BEFORE UPGRADING.
b) If you have a NetGear A6210 Wireless Router (it may be the case with others as well), UNPLUG IT before upgrading.
c) If you have an NVidia card (I have a GTX 970), DOWNLOAD THE DRIVER released on 7/29/2015 and keep it aside.
d) Download the LATEST wireless networking driver if you have such a device and keep it aside.
e) After the Upgrade, go into your device manager and uninstall and remove the wireless networking driver (this may have been copied over from your previous OS).
f) Install the latest NVidia drivers (when I did, my resolution went back to normal and my 2nd monitor started working).
g) Install the latest Wireless Adapter drivers (I had to unplug my device, uninstall the drivers, re-install new drivers after the upgrade and plug in device before it worked properly).

Fortunately, if anything goes awry, you can use the F5 recovery mode and "restore previous build" which actually restored my Windows 7 (and it was fairly quick to do compared to the upgrade itself) back to its initial state (thankfully!). I had attempted to upgrade and rollback two times prior until I gathered all of the information I presented above which got me back up and running.

I do have to say that it is much snappier, sleep and wake are much faster, applications appear to load/cache faster. However, not ALL of the icons/folders I had in my Windows 7 installation are appearing in the Windows 10 Start Menu --still looking into that.

If you can spare the space and you attempt the upgrade, don't remove the backup of your old OS until you've kicked the tires a bit. I'll give it a few weeks and if all is well, I'll clean up the old Windows 7 installation. However, I still have my original Windows 7 image I made before attempting the upgrade, I'll probably image Windows 10 too after all seems well and doing a cleanup.

Good luck!

Thanks for this,hope some useful information comes in.

Well, aside from the wireless not working (actually causing infinite loop reboot on initial log-in until I unplugged the wireless device) and locking up the "WiFi" settings (until I rolled back and removed the VPN client), there was also having it kick my screen resolution down, jumbling all my desktop icons and not recognizing the 2nd monitor until I re-installed the latest NVidia video drivers under Windows 10, everything was much better after that.

However, the issues I ran into were through the course of two upgrades, two roll-backs and then a final upgrade when I had finished researching others' having upgrade issues and finally getting my ducks in a row.

I've used Windows 7 at home for quite some time now and I use Windows 8.1 at work, so at least Windows 10 doesn't feel completely "foreign".

It's more of like the 'best of both worlds' and I'll keep it as my daily driver if I don't run into anything egregious over the next two weeks.

(Posted this in another thread before I found this one.)

I did the dive today and so far I'm mostly positive.

Problems so far.

1. Chaos Gate doesn't work properly.

2. The install needed a extra restart that it didn't prompt for. Had resolutions problems and so on, it looked like it was in safe mode or something so I rebooted. Fixed it.

3. Comodo Firewall doesn't work yet.

4. Windows Updates are apparently downloaded and installed automatically and I can't find a way to turn it off.

5. Windows Security is confusing. Turned off realtime protection to see if that interfered with Comodo Firewall not working. Now I can't turn it on again and it says it will automatically turn itself on after a time. Where the heck is Windows Firewall or what's it called. Does it even exist in Windows 10? And so on.

Edit: The same here.
I upgraded from Windows 8.1 with the "mod" Classic Start Menu installed. I wonder if that have something to do with it?