Do Not Hide the XML!
Periodically, I encounter vendors of XML authoring tools who delight in proclaiming that their products "hide the XML" from users. They make the seamingly reasonable claim that XML is technical, complex, and disruptive. Certainly, subjecting authors and editors to the XML syntax is both intimidating and dangerous, and for this reason I would never attempt to convince anybody that XML documents should be created or modified using text editing tools or general-purpose word-processors.
But at the other extreme, I have also never been convinced by XML authoring tools that try to hide the fundamental nature of XML documents from authors. To me at least, they are more clumsy to use than the ones that reveal and even promote their XML-centric nature.
In order to be able to create worthwhile XML documents of any complexity at all, authors need to understand what they are producing. They need to appreciate that XML divides their documents into sequential and hierarchical structures with meaningful names, and they need to check the boundaries of the structures they create. Their task is made easier if they can see the choices available to them at any given cursor location, and they are able to change the context just by re-positioning the cursor within the structure of the document.
I strongly suspect that the two most successful XML word-processors on the market are XMetaL and Epic Editor, and both of these tools show the XML structures within the text. After a few hours of tuition, they are easy and productive to use. Authors soon start to consider their approach natural. Even Microsoft is now beginning to get in on the act with Word 2003 Professional, though this tool is not yet a true XML word-processor (for reason why, see the Word 2003 article in this area of the site).
I became a convert many years ago, when I began to learn SoftQuad's Author Editor (now XMetaL), then used FrameMaker+SGML's authoring interface to write all of my books.