Most users have encountered the hierarchial organisation of elements with the interface I use. I'm not saying HierMenus is useless, only that I find it a bit less user-friendly. My system is maybe also slightly less user-friendly than Joust, because mine doesn't come with a help system. The owner of a web site can freely ad a link to a document explaining the menu if he wishes, but it's not a built-in feature. The concept of frames on a web-site isn't new, but it's a controversial subject in many communities.
Some people endore the technology, others think it's totally useless.
In my opinion using frames in a menu system is also debatable, just as the usage of frames on a regular site is. I've chosen to use frames for my menu since I believe it works nicely, makes me able to write code easily, and I am able to give the user a consistent interface throughout the navigation of a site. The user has the ability to change the content in the menu, but the content doesn't disappear between pages. The concept of one frame being changed while the rest stays put is one of the reasons why frames at times is used, and here I'm able to make it useful. HierMenus is a system that works without frames.