There was a bit more manual interaction required than i would have liked (e.g. when it absolutely refuses to remove the last copy of a bookmark in batch mode, forcing the user to delete them individually). Also, the URL checker process pops up countless HTTP auth dialogs for sites which use HTTP Basic authentication. i'm not certain that this extension can avoid those, but it is irritating (i've got dozens of them). In any case, it's simple, clean, and easy enough to use, and it allowed me to go through and clean up a great many useless bookmarks.