Yeah, I’ve used for a few comments. The only issue it has, is that the html it produces needs to be edited heavily if you re-edit it from the WordPress web interface. Otherwise its very nice to use. The most useful bit being the drag and drop selection of words from a web page into the editor box.
Have you given it a spin? It'd be nice to have something like this because the Blogger "BlogThis" function is inherently br0k3N within Firefox at present. Be interesting to know if you've found this worthwhile, or if it's just junk 🙂