I've installed the plugin in Joomla 1.5.22.
Tested it and found out that it does not work correctly with Iphone. The submenu items do not get displayed. Asked about this to their support forum but the response is slow and still there is no solution. In the meantime tested it on an android phone and the submenu got displayed correctly. After changing to another submenu and going back to the 1st submenu it also does not get displayed.