This plugin works as advertised as soon as you install it. It has dozens of pre-configurated variables that you can change. However, you don't need to change a thing in order for it to work.
It is easy to use, and, most of all, it does the job flawlessly.
I had a problem with maps not showing up in Firefox and IE and emailed the developer. Few minutes later I had a reply from him that fixed the problem in three seconds! It was a bit of CSS code in my template, written by me, that was messing it up. It had nothing to do with the plugin.
If you need a Google Maps plugin for Joomla look no further. You will not find a better one.