I purchased this mouse and have been using it for about a week. It takes a day or so to get used to (my back muscles hurt after the first day of use), but now I love it. What a smart design. It makes those "other" mice so ancient!

I did not have pain in my hands, but at the end of a day of mousing, my muscles on the top of my hand felt tired (I had already gotten away from the traditional mouse and was using a track ball instead). The twisting of my hand was still uncomfortable. But I noticed if I held the track ball in my hand as if giving a hand shake, my hand felt immediate relief...but the ball kept falling out. So I decided to try this vertical mouse and would never go back! Thank you 3M!

Revise: Now that I have used this mouse for a while, it is still comfortable. The only complaint I have is that sometimes, when you least suspect it, the cursor jumps to a different part of the screen. This does not happen all the time, but it happens. In the instruction manual, it states that the optical sensor performs best on surfaces which have visible detail (huh?) and won't function well on smooth surfaces (glass or high-gloss finishes). I had the mouse directly on my computer table (fake wood). After putting the mouse on a mouse pad, it seemed to correct the problem. It is precise and does not jump. In the manual it even shows the mouse being used on a mouse pad. OK, problem solved. This mouse is great!

Very uncomfortable, Waste of money. I do computer production work and thought it would keep my wrist from dragging on the mouse pad. It is not useful at all for high speed mousing.

A product that truly works for sufferers of "tennis" elbow from mousing. Easy to use. I love it!

I have arthritis in my fingers, and the vertical mouse leaves my hand feeling very comfortable and relaxed. An unexpected side effect is my whole arm feels more comfortable, since palm down is an unnatural position for the hand. Palm facing center is more natural. It's important to get the right size. This one fits my hand great, but would be too small for a large hand.

Love it. This is the third one I have ordered. There is a learning curve involved as you get used to it, but it eliminated the numbness and tingling symptoms I was having with a regular mouse three years ago.