The default is still Unsorted bookmarks! Rated 2 out of 5 stars
No problems with crashing but... It doesn't change the default bookmark folder in the pop-up dialogue or the one-click Bookmark link. I thought that was the main purpose of this extension. There really is no other use for it. (Firefox 24.)
I can add bookmarks to folders in one click without this addon. I added my preferred folder to the Bookmarks Toolbar and enabled it. Now I just drag any link or Tab to that folder. You can also drag it to the bookmark button and it will open folders as you pause on them. Alternately, you can open the bookmarks sidebar to drop a lot of links, and organize them.