I was originally sceptical about this mouse having previously bought a trackball which was also meant to be more ergonomic and reduce carpal tunnel syndrome and repetitive strain injury. Having tried a trackball for three months it was actually making my arm and wrist ache more and I was desperate to find something that worked.
Having researched a lot before I bought, I could see the advantage of buying a mouse that keeps your hand in the "handshake" position because it is much more natural.
While it took a little bit of getting used to, it was quicker to get to grips with than converting to a trackball and within a week the pains that I was getting in my wrist and forearms had already started to disappear.
I have now been using this mouse for about 6 months and I can honestly say that I will never switch back to an old type of mouse.
I think the main difference between this and some of the other options out there is price. This is very reasonable compared to some of the ergonomic mice produced by well known brands like Logitech and unlike some of the Logitech mice I have used in the past this one does not disappoint.
There are two downsides that I have found through using this mouse.
Firstly, the scrolling button under your fingers is meant to perform the same function as a mouse wheel, but does not work very well and usually just results in performing the same function as a left click rather than scrolling or zooming.
Secondly while 3M have since brought out a wireless version of this mouse there wasn't one available at the time I bought mine and while I would have paid a little more for having a wireless mouse, I think that the wireless version is much more expensive. However, if like me you use a mouse all day then I would definitely recommend getting this one.
Excellent product - good quality, easy install etc. Has completely eliminated the aching fingers I used to get after hours in the office using a standard mouse. Now all I need is one for home!