Each time you update the order when you have thousands of posts it will literally destroy your disks IOPS. If you wondered why your AWS RDS was running out of IOPS, this plugin is the reason it is happening, it will update each and every posts menu_order meta, which if you have 15k posts is 15k queries to the DB.
Having a news site and 2-3 authors posting new stories every 30min to an hour will equal 45 000 queries to your db, rapidly eating your IOPS and your site will fall over. if you are using a hosting provider and they keep pestering you to update and charge you more, this is the reason why.
If you have a small site with few posts, this is fine. If you have a huge site, do not use this plugin or if you plan on having a huge site do not use this plugin until they fix the indexing.