Installation was flawless.
According to Task Manager I'm now using a lot less CPU power to do things.
That fucking awful tiles screen is gone.
The Start button is not only back, it also does more useful things than ever before.
Doing things is much, much faster than on Windows 8.
It is very intuitive.
The bottom taskbar has been improved quite a bit.
I still can't figure out how to get Cortana to respond to my voice. I think this is because I spoke too quickly during the part of the set up where it asked me to read a sentence outloud. I can't figure out at all how to get to reread that sentence again.
I had Windows 8 set up so that it would launch without me typing in a password. Windows 10 required me to set up a PIN.
Cortana obviously knows a lot about me. To the point of suggesting "Anakin" as my Cortana name.
I have my laguage settings on UK English because many of my clients are from the UK. But I had my keyboard set up as a US keyboard. It has now made it a UK keyboard. This is annoying but workable.
UPDATE: Got Cortana to work. No idea what I did to make it work but it does work well.