WP Media Cleaner failed to recognize files that were attached to slider plugins that link to pages, and failed to recognize images that are manually attached to a page in WP media library but are not present on a page or post. There are no filtering options, one has to manually check each file to be sure it's not important, and I found that manually using the WP image library / unattached files menu and tools was just as fast. Therefore I found it pretty much useless and even dangerous for a novice.
WP Media Cleaner needs more development before I would consider it a useful plugin for a business website. It may work fine for basic bloggers and those using their site to present their photographic images.
Yes it's a "simple" plugin but all developers should offer clear instructions on use for those with little experience with WP and plugins. This developer does not. The plugin home page is simply the authors personal website.