I'm not a web developer, just someone with basic knowledge who looks after the website at a small organisation. This plugin helped us migrate a site with 200+ posts from Joomla!? 1.5.2 to WordPress 3.5 with very little pain.
It was very simple to use, with clear instructions, and worked first time. Most importantly for me it transferred menus and sub-menus to wordpress categories with the structure intact.
One note: We had used Joomfish to make a bilingual site and the plugin also imported all translations as posts in the correct categories, but without differentiating languages, so of course we had to deal with the business of turning these into a wordpress site with language switching.
Overall, though, it basically worked like magic. Within 20 minutes of downloading the plugin I had a recognisable website in WordPress. Our WordPress theme uses featured images, and the main images from the Joomla!? posts were all imported as featured images, which might not suit everybody but was perfect for me.
Many thanks to the author for this excellent plugin!