What is KDE Neon, in simpler or more practical terms? How's your experience with it?

I have read the FAQ of KDE Neon: it is well made and answers ground questions like "Is it a distro?" or "Can I turn Kubuntu into KDE Neon?"

...And yet I'm confused, because I'm just a newbie in the Linux world. For instance, when they say "on top of a stable base" I don't know what's meant as a "base".

I think I understand that it isn't a distro, but it fascinates me that it's meant to be installed from an ISO or similar, just like a distro.

I wonder if any of you can explain:

• What is it, in different words?
• Why is it "implemented" as it is?
• Are there any other "quasi-distros" like KDE Neon out there?
• Do you use it? how has your experience with it been?

Cheers!