I bought this mat on the basis of other reviews, which rate it very highly. However, when I tried my Microsoft optical mouse on it, the screen pointer went skidding off in all directions!
When I looked at the packaging a bit more closely, I found that this mat has a high grip surface designed for TRACKBALL mice. The hard plastic surface has tiny indentations which gives good grip, but drives the laser signal crazy. However, rather than go to the trouble of returning it, I carried out a modification by sand-papering the surface down. It worked.
But then there is another aspect which isn't so good - the smell! I also bought the keyboard pad (same gel material) and as soon as I took them out of the packaging I noticed a pungent smell of something akin to damp carpet. It's really gross and has permeated the whole house. After three weeks, the odour is just as strong and so I will probably dump them.
So, all in all, if you have a trackball mouse and no sense of smell - get it. Otherwise, steer well clear!