1. Did you upgrade after the release of Windows 10?
Upgraded last night.

2. Did the game start with zero issues?
Once I got my driver issues figured out, no issues.

3. Running DX11 version of the game just fine?
Seems so.

4. Noticeable changes? (Game wise)
Only spent 2 minutes in game to test before going to bed, but nothing seemed out of the ordinary (all my settings were still there, so didn't have to change anything).

5. Personal experience you would like to share about it? (Windows 10 / FFXIV with W10)
After the upgrade my second monitor wasn't working, and I noticed the computer wasn't recognizing my GPU (NVidia GTX 960). I had the latest driver installed before the upgrade, but that alone didn't seem to do it. Downloaded the driver installer, and had it do a clean install to get rid of the extra fluff. It never actually got to re-installing the driver because cleaning out the fluff and the mandatory reboot seemed to fix my issue.

6. Clean Install?
No.