This plugin is very useful, because it adds a page to the plugin menu. This page shows a list of plugins which have been removed from the wordpress.org plugin repository. Therefore, you can easily identify plugins which will probably not receive any updates anymore. For single-site installations, this plugin deserves five stars.
Unfortunately, in WordPress multisite, the page is shown in the site administration backends instead of the network administration backend. That makes it a bit inconvenient for network administrators to check which plugins have been removed from the plugin directory.
Moreover, the page in the site admin backend can be accessed by any user with the manage_options capability. This includes site administrators who are allowed to adjust the settings of their site, but who are not allowed to install, update or delete plugins in the multisite network. In multisite, it would probably make sense to check for the install_plugins capability instead.