Best product I have tried on glass shower doors.  A++
I bought this after hearing about it on a home improvement radio show.  Thought it a bit pricey, but it did an amazing job on my shower doors and I used about 20% of the product, at most.  I have tried many things that claimed to remove hard water spots, but none completely worked.  It took some rubbing and about 20 minutes of work to do two doors, but they look like new and seem to have a water shield on them now and water runs off in sheets instead of beading.  Also used it on a ceramic sink and cleaned it instantly.  It is a powder and you use it on a damp cloth, so it spills off a bit and makes a little mess, but cleans up easily with a wetter cloth at the end.  Very satisfied with performance.
Rating: 5 stars