Works almost perfectly, but... Rated 4 out of 5 stars
It works perfectly in FF3.6 (and older) on Windows (XP). However, in FF7 on Linux (Lubuntu 11.10) it fails to block the scripts from hiding the Bookmarks Toolbar, i.e. unchecking the "Hide the bookmarks toolbar" has no effect. This probably has something to do with the new toolbar scheme that FF introduced in newer versions.