Here is a good overview that touches on modules, templates, page layouts and free plugins. There are literally hundreds of free plugins (he uses docman as an example). Free templates, etc. It took me about an hour to get a pretty good feel for it. I have extensive experience in website design, html, perl scripting, macromedia web development tools, etc. I also had websites I built from scratch with shopping carts. Since finding Joomla, I would never build a website again without using some sort of content management system like Joomla. You can incorporate your google maps, keep pics in whatever directory you want, etc. It's all flexible.
If you use godaddy or many of the popular hosting sites, Joomla is a free add on and they install it all for you.
http://www.youtube.com/watch?v=Htdawgn_79g