This varies greatly from framework to framework, and language to language. On the JVM at least, the dark machinery that handles the XML is rather rigorously correct. Parsing and generation are trivial, especially using JAXP. You have multiple ways of working with XML (objects, DOM, push, pull).

XML is "good enough" for a lot of cases. There are lots of tools to mess around with it too, which is really quite valuable when you're experimenting with various kinds of data or you're debugging. Being able to extract out stuff you're interested in XML format means you can perform a lot of complex manipulations quite easily.