As soon as Windows 10 came available I forced my Acer W4-820 -tablet to download and install Windows 10 on top of Windows 8.1. You can read how anyone can make PC fetch the files needed and boot up the latest operating system from Microsoft.
What I wanted to see was the migration from one Windows to another. It was never before advised to install new operating system on top of another. Well, install went just fine and took about 45 minutes. Afterwards Windows 10 downloaded drivers and as fas as I know special software for tablet use. How do I know? Icons got bigger. Now it's easier to tap them.
So far Acer W4-820 has behaved ok (about 1-2 hours ;D). It's up to Microsoft from now on. What I've heard is Microsoft will force all of us to receive updates for Windows 10. Let's hope all those updates work well!