I have used it for toilet ring and hard water behind the sink before, but yesterday I used it to scour the entire tub, and I am thrilled with the results!  Not a trace of soap scum, nor hard water spots.  Yay!  Took a lot longer than Comet and a sponge, and took off my finger prints, but soooo worth it.  Of course, it does not disinfect so one must still wipe it down with Lysol, but for pure shine and sparkle ya can't beat it!