Joomla offers web site owners and developers great features and benefits. Joomla! is free open source and available to anyone under the GPL license. Great new features and improvements are added with each release. With the help and advice of an incredible user community Joomla has become an award-winning application. Remember, the official site for Joomla is at http://www.joomla.org - I highly recommend reading through their discussion forums and community sections. Joomla is well supported by a community of developers and service providers. Most web hosting service providers support Joomla installations. In essence, Joomla is fast growing with a great support structure. One of the best things about Joomla! is how easy it is to add or modify content, including images and multimedia, and organizing and managing important data. The real power of Joomla is found in the application architecture that enables thousands of developers around the world to create powerful add-ons and extensions to this powerful content management system
I like Joomla. I work with this CMS few years and I like it. This software is flexible and user-friendly. Joomla is enables you to build powerful Web sites and online applications. It is free and available for web community. You will always have upgrade software, because Joomla web developers fix bugs and upload new realeases at official website Joomla.org. You can find all necessary information at the website how to atart use the CMS.
One more thing to add: DO NOT GO FOR JOOMLA 1.6! It is to early, most of the components, plugins or templates are not compatible, fully or partially. Best companies usually added compatibility or native support, but smaller players didn't. So, go with Joomla 1.5.23 for some time...