I use the Sphex on a glass table the pad is therefore great even after 3 months there is no slipping mm, I can because table clean with glass cleaner that makes the pad nothing.
But it should be a quite clear when the surface is a bit rougher as wood surface that her pad so not 100% holding as on glass.
Also, keep in mind that this pad should be at a place more permanent who like to change its Sitzpositzpositon and therefore want to lay down the pad is different here wrongly advised that does not make it long with. (I can recommend the one that Goliathus)
+ Absolutely flat, flat does not work
+ To prevent slipping on smooth surfaces (glass with me)
+ Mouse slides imperceptibly over the pad
-Nothing for people who constantly want to sit differently on the PC, the constant tilt dislike it safe.
-Absolutely nothing for mobile use (with the laptop with you)
Conclusion:
For me super on a glass table with a Razer mouse, it is really the best compy.