Everyone should have one, and those who are MD/RN/etc should so they can tell their patients about it.
I have been a RN (and a USN Corpsman) since the 70's and wish I knew of this years ago.  So many patients I could have recommended this to.  I found the way it is in the picture did not work for me, I tried the curve part actually away from the toilet and with the toes up (you can have toes down and that felt weird) ... with the curve away from the toilet it made it easier to use.
Rating: 5 stars