I don't own a esd mat and am novice familiar with esd standards....so take what I say cautiously (get real opinion).
1. This is just the conductive layer (most have 2 or 3 layers, with dispative surface+conductive surface)
2. The mat isn't s20.20 certified.
3. The resistance is on the low side I think (low enough that I think many places would reject it). For ESD control, you want to remove charges....but not too quickly, because that in-itself can damage components. Also for personal safety reasons and you dont want it shorting or messing with your circuit (the point to point resistance on that mat is only 34K ohms!)
http://nz.rs-online.com/web/p/esd-safe-mats/7873111/Not 20.s20 certified, but the resistances look a lot better to me