Using whitespace was a mistake. I know all the kids love it but it's just wrong. I've never had as much difficulty explaining json or xml to users as I have yaml.
We seem to have something in common: there is a serialisation form, we strongly dislike. But what I cannot understand is: why the heck would anyone torture anyone else to read or even write XML? XML is the absolutely worst configuration language I can imagine. I mean: when is something an attribute, when a tag on its own? What is even a list? And don't forget to include a full HTTP URI for the namespace, otherwise the tag is not defined.
By the way: all valid JSON is valid yaml as well. So in theory, you can use yaml as JSON with comments.