I enjoy JSON for internal stuff and where it does not matter that JSON is not very expressive. JSON Schema is a poor substitute for a proper schema. For anything where I am interfacing with another person or team, I send them a DTD or XSD, which documents the attributes and does not have nonsense like confusing integers and floating point values.
For quick and dirty, I agree about JSON. For serious data interchange, I use XML.
For quick and dirty, I agree about JSON. For serious data interchange, I use XML.