Works well on my desk but after a while when you lift your wrist off the pad there is a crinkling sound like the inner padding is surrounded by plastic.  Using this on a tray on a sit/stand desk the mouse doesn't track very well even though it appears to be flat.  I'm using the Anker 2.4G Wireless Vertical Ergonomic Optical Mouse, 800 / 1200 /1600DPI, 5 Buttons - Black.