[zwerdlds]

We are using it at my current place of work with https://github.com/jdorn/json-editor to generate simple administrative UIs for backing configurations for non-technical users.

It's not a fantastic UX but it works and it's fast to develop.

The docs are sparse but for my money the format is relatively intuitive. I'd prefer to be using XML/XSL/XSLT as they are FAR more powerful, but that's just what you get with JSON.