At first I hated it because it wasn't readable enough. Than I've learnt that schemas and their support in IDE's are great and started to like it. It's much easier to write e.g. configuration in xml with schema validation and completion than let's say yaml or json with docs .
Yeah, I wish new data transfer formats would take inspiration from the schema stuff in XML. That's one of the things it does really well, despite all the other terribleness mentioned in this thread.