I tried both Google Takeout and the built-in feature from Google Docs that lets you download your documents. Even if they have the same purpose, they're quite different. The Google Docs feature is more flexible: you can choose to download only spreadsheets or presentations and skip all the other documents. You can also skip the files uploaded to Google Docs and not converted to a Google Docs format (for example: PDF files, archives and video files). Google Takeout has a "configure" feature, but you can't skip one or more document types. Another subtle difference is that Google Takeout lets you export only the files that you own, while Google Docs exports all the files from your account.
How to export all your files from Google Docs? Just go to the Google Docs homepage, select one or more documents, click "More" and then "Download", click the "All items" tab, pick your favorite formats and click "Download". The process is not that intuitive and you shouldn't have to select a file to see the download option.
{ via Data Liberation Blog }