You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allfileusages gafcontinue="Barcelona3.jpg|1480" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1469" ns="0" title="France 2002 Montpellier" />
      <page pageid="1480" ns="0" title="Spain 2003 Barcelona" />
      <page pageid="1563" ns="0" title="Miles Wedding" />
      <page pageid="1744" ns="0" title="Norway 2005" />
      <page pageid="1853" ns="0" title="Photo Gallery" />
      <page pageid="2152" ns="0" title="Italy July 2006" />
    </pages>
  </query>
</api>