The plugin immediately re-arranged some of the existing menu items, without my intervention and without me wanting it to. The first item that I tried to make visible only to the top level admin role was still visible to the editor role, so I gave up an uninstalled.
It didn’t exactly fill me with confidence, and I’d be unhappy using a plugin that was so unpredictable.
This functionality really should be added to the core and the GUI along with the “Members” plugin functionality. Customisation of the admin area is essential for live client projects, and shouldn’t be left to individual developers who have insufficient time for proper testing. It’s too important if WP is to be seen as a proper CMS.