Rated 4 out of 5 stars
This is really very handy, especially when combined with the 'Add Bookmark Here' add-on. Combine the two, and it becomes simple to file away bookmarks both quickly and precisely.
It's good, but it could be *great* if only there were more options available. It would be nice, for example, to be able to choose whether the submenu should appear at the top or the bottom of the context menu. Also, as many others have said, the ability to choose a different folder as the root would be nice, given how much variation there is in how people prefer to organize their bookmarks (although for those whose bookmark ontologies are based on Unsorted Bookmarks, the "Unsorted Bookmarks Folder Menu," which puts the Unsorted Bookmarks Folder inside the Bookmarks Menu, clears that problem right up.)