After several years of typing on small keyboards in bad chairs, I developed a nasty case of RSI. With this mouse and an ergonomic keyboard, I am pain free and VERY happy.
I would advise anyone who uses a computer for hours at a time to invest in one of these BEFORE the problems start, not after. You would save yourself a great deal of unpleasantness.
This mouse can also be used for gaming, scrolling, it is highly responsive and exceedingly comfortable.
Every one of my friends who has tried it (and they all want to) have found using it to be very intuitive, and adjust to it in a very short time.
Thank you 3M, without this mouse, I would probably have had to give up my chosen career, because the RSI was so painful.