One thing that ticked me off in 1.x was when using the System.Xml.XmlValidatingReader, the ValidationEventHandler's ValidationEventArgs doesn't expose the underlying XmlSchemaException (marked internal) which has all the useful info like linenumber and position. Instead you're expected to parse this out of the Message string property or use reflection to dig it out. Not so good when you want to return a more sanitised error to the end user.
