Hello. I have tried for a bit to get this working, but haven't had any luck. Initially, I was getting MySQL errors but finally realized that I needed a database user with authorization on both (duh). So then I ran it, and no content was imported.
What WAS imported were thousands of users never activated on my Joomla site, which was weird. Since they were unconfirmed, they were all spammers... so after spending hours cleaning up my users before importing to the new site (I imported users first in the hopes that this plugin would connect their content to their user names), I now have thousands added and need to remove them from my WP site. That was just weird. Also very inconvenient.
In the end of that attempt, I got to a page that simply says:
Joomla To WordPress Migration - Status Messages
Below it, there is nothing.
I tried to run it through with just one category, but the same thing happened. Status Messages with nothing below it, and 6K spam users imported instead.