I was a bit hesitant to purchase this as folks were reporting it was not stiff enough for a deep carpet. This mat is much stiffer than the last "deep carpet" mat I purchased. I find it to be plenty thick enough for my deep carpet. I'm 250 lbs. and I can roll around easily and sit in one place without the chair wheels leaving any indents.
I've had this mat less than a month and it has four divots for my chair wheels. The mat doesn't stay in place so once or twice I day I move it back toward the desk. I wouldn't buy this again. I gave it two stars instead of one because at least I can roll my chair now. I expect this to crack within six months and I will buy a better quality mat.