Like you say, it's free, try it out for yourself.
However, from experience I can tell you that hiring a good expert in the CMS of your choice, can really save you lots of headaches. Whether it's Typo3, or Drupal, or Plone, or Joomla, a good expert can set up the templates, organize the pages, and give you advice/support on managing the site. I am not an expert in any of these CMSs, but have worked on projects involving them enough times that I recognize the value of a good expert. It can be like hiring a magician, and far better than trying to learn a programming and coding your own CMS. (I have coded my own CMS's for custom situations, but an off-the-shelf system generally does what most people need.)
(My current CMS of choice is Cascade, which is a commercial product and based almost entirely on XML/XSL to output just about any data you want: XML, XHTML, PHP, JSP, ASP, PDF, whatever. Really powerful, although XSL is a cruel lover if you aren't careful.)
Having said all that, I'll share this advice about Joomla:
- The built-in text editor is junk. Find and install JCE. The core JCE functionality is free, though the commercial add-ons for image management are worthwhile if you manage a lot of graphics in the site. Like a lot of things about Joomla, JCE adds features that should have been there in the first place.
- You need the Extended Menu plug-in if you want to do any useful CSS menuing like Suckerfish. Even though it doesn't handle SSL links right (they get menued as HTTP instead of HTTPS), it's still totally worthwhile. You can fix some of the HTTPS stuff via an htaccess file if necessary. As above, this adds a feature that should be already part of Joomla.
- I have never, ever, ever been able to get any of Joomla's community extensions working right. None of them. It's a good thing that I don't run any community sites and have only experimented with them for family or clubs I'm in.
I've written Typo3 extensions before (in PHP obviously), but must admit that I detest TypoScript. It always feels like a hack.