Searching HN for past discussions on Joomla, you see mostly negative remarks....
http://www.google.com/search?q=joomla+site%3Anews.ycombinato...
Searching HN for past discussions of Drupal or Wordpress, you get a lot of positive remarks and lively discussions about the pros and cons of each system... just as you would with most any technology.
But Joomla seems mostly negative yet it is the second most popular open source CMS in use! Why do people use Joomla?