Joomla is nice, but I've found that as far as CMS's go, It's really hard to beat Drupal when it comes to sheer functionality. I've just spent a while throwing together a new Joomla website, but kept coming up on petty issues like user group handling and comments functionality. A lot of the Joomla Extension/Module developers have adopted capitalism in it's finest form, which is fine since I'm willing to spend a bit of money to save some time, however you will find your choices quite limited.
Joomla styles have hands down been some of the best I've seen in a CMS, but that's not enough to keep most people's attention after they find themselves wrestling with the mundane details. Great CMS, but it still is a long way off from being my 1st choice yet.
