I received a parse error when I tried to activate the plugin. I changed line 658 of joomla2wp-mig.php
from this: foreach ( $wp_posts as &$item )
to this: foreach ( $wp_posts as $item )
and the plugin activated, no problem.
Unfortunately, I had forgotten that I didn't delete a bunch of the sample content from the initial Joomla install, and that got migrated over as well. Otherwise, nice time-saver.