Be careful to use this plugin with NextGen Gallery. While deleting Draft data ALL records from wp_posts table are deteted that have post_status='draft' value.
The issue is that NextGen Gallery plugin stores own data in 'draft' records with post_type values like 'ngg_album', 'ngg_gallery', 'ngg_pictures'... After they are deleted you see just messages 'Gallery not found. Please check your settings' on your site.
Possibly it make sense to delete only those draft records that have post_type values 'page' and 'post'.
Another proposal - on the Admin page to add a note on top like 'Please make a back up copy of your database before using this plugin'. In my case it would help a lot :)...