When I purchased this mouse (it was only $16 at my Walmart!), I was highly skeptical considering there were not many reviews. I am a fan of Logitech, so I did have some faith in the product.
Lo and behold when I got home and opened the package (which has an easy open back - amazing!!!) and plugged the dongle into the computer, the mouse worked right away. No software required, no annoying pop up acknowledging that it was plugged in.
The first thing I did was test the distance. I set my laptop on my bed and left the room into my hallway (about 15 ft away, separated by walls) and to my astonishment, it worked just as well as if I were next to computer. Despite the other reviews, the mouse is not nearly as small as I thought it would be. It's about 2"W X 3.5"L X 1.5"H.
I highly recommend this mouse. If you get one and it doesn't work, then take it back and get this one again. Great price, great value. Gratz on another good product, Logitech!