I'm using it at the moment, but too early to tell, but it has had VERY positive feedback from some of the barefoot people (who aren't easy to please!).
They also do it in powder form which is the one I used - just depends what your horse will eat. A warning - some horses apparently object to the stuff, although weirdly my ultra fussy pants mare loves it!!
Their on line order facility is excellent and very quick delivery, but you can get it at some feed/tack places.