… did not go well.

After installing over night it needed another half hour or so to “just finish off a few things”, after which it briefly displayed the desktop, followed by a message saying that it was going to have to re-start because of an “INTERNAL_POWER_ERROR”.  Over the next half hour or so it repeated this three or four times.

Luckily someone here had the same problem and posted a very simple solution:

• As soon as the “Windows” icon appears in the bottom left corner, right click and select Device Manager (or hold down the Windows key and press x).
• Select Display adapters, double click the AMD driver, select the Driver tab, and click the disable button.

After that everything worked just fine, although re-starting was very slow.

Strangely, I have just checked the drivers, and the AMD driver seems to have re-enabled itself; but everything is still working.

As for opinions on Windows 10, it’s just an operating system.

Edit 4th August 2015:

I was going to say that at least the pdf content indexing and preview still worked, which it did on the day I did the upgrade, then yesterday the pdf preview stopped working.  No messages, just a blank space where the preview should be.  Looking at the Adobe site I found they now have a reader called Acrobat Reader DC, which I installed, and it worked.  I can’t say I like the new interface much, but it does the job.