I use it - swapped from a more expensive product. My big mare has a history of lameness of unspecified (although with much expensive investigation!) nature. I haven't noticed any difference since swapping her, and that was over a year ago.
My bone spavin horse has been on it for over a year on a friends recommendation. Of course its one of those things that you can't see if it works or not really. My horse is sound but I'd rather hope he would be after joint injections, adequan, and three lots of Tildren.