i disagree with Michael, it is very simple to use joomla backend to change templates and manage websites. Once taught, what is where, any one can use it.
Sometimes people find microsoft word very hard to use(they actually take lessons to learn it), but this does not mean that it is actually difficult to use. Same goes with joomla or other CMSes.
When i compare joomla with drupal etc, my feeling is that joomla is a lot of friendly to novice users while drupal is friendly to intermediate to advance users who would like to have more control over things.