You can now convert your Joomla 2.5 site to WordPress by using the FG Joomla to WordPress plugin.
The free version converts all categories, articles and images.
The Premium version available at: https://www.fredericgilles.net/fg-joomla-to-wordpress/ can convert users, authors and Joomla 2.5 featured images. And it keeps the SEO by automatically redirecting the Joomla URLs to the new WordPress URLs.
