I currently own one. it is on my 300 rum sendero. I wanted a heavy stock that I could add weight for added comfort for bench shooting. the stock works great. I had to do some work to it though. the grip is extremely rough. on bare hands it is very uncomfortable. I just sanded it down smooth. the thing I like about this stock is that with the money I have invested in it I don't feel guilty if I feel like doing some work on it myself. but, I have the luxury of changing the stock back to the original HS Precision stock my rifle came with.
I have not regrets getting this stock. I had considered a McMillan but could not see spending $400-500 for a stock I wanted to ream out and add weight to. the ultimate sniper stock is not perfect. but then it is only about $160. if my rifle did not have the recoil and I was not planning on adding weight, I would have gone with a McMillan.
some people like the ultimate sniper stock, some people hate it. I read up on it before I got it. no regrets for me.