I use them, 2 at each corner.
Considering the worn out crappy shocks I upgraded from they were a huge improvement at a budget price, however I can't say exactly to how they would compare to bilsteins or other high end brands.
I was really surprised at the improvement in ride and handling when I added the dual shock kits at each corner. If you are thinking of upgrading your shocks, I'd reccommend installing the dual shock kits at the same time.