Why do you buy a mat? So chair's rollers won't press into carpet and chair will roll easily. Neither happens with this mat. The castors will dig into the mat and chair will not roll. If you don't get up and move the chair periodically it will dent through the mat into the carpet. I weigh 165 lbs so nothing out of ordinary there.
This mat should only be used on very thin carpeting. The description says low pile and that is very important. The cleats make it unsuitable for bare floors.
The comments about sum it up. A larger one would be nicer but this is adequate. It has the same anti-static benefits - also the same "keep the carpet clean and unworn" benefits as the more expensive brands. The main thing I would say on this is that it could be bigger. Hence the "adequate" rating.
We have it on thick carpet and it is too soft the edge curl up when you roll near an edge. Also the teeth aren't large enough to bite into the carpet so it slides around.