As an application, Joomla! 1.5 boasts remarkable advances over Joomla! 1.0 in the areas of extensibility, usability and internationalization.

Joomla is now up to version 1.59. You should upgrade from all other 1.5x versions to 1.59 which was a bug fix and security release.

Building extensions is vastly easier and faster because of the comprehensive new API. The simplified user interface eliminates unnecessary clicks and context changes for site administrators and managers.

Support for extended character sets, right to left languages, and translation of all static text in the front end and the administrator allows enhanced internationalization and worldwide use. New options for use of layout overrides and template parameters give designers total control over the look and feel of sites.

While this release marks a major milestone in Joomla history, it also marks a new beginning. The next phase offers the opportunity to bring together the code created, lessons learned, and momentum gained, to build something truly great. It took tens of thousands of hours, thousands of revisions, and hundreds of people to get to this stable point for version 1.5. (Updated January 2009 to reflect the latest Joomla version 1.59, Joomla 1.6 is very close)