I am actually using it to protect an area my cat likes to dig into the carpet. The pokey things keep the mat in place perfectly and help protect the area of carpet the cat fancied without creating a tripping hazard.
First the BAD ... it was delivered without a box. I woke up and found the thing outside my front door unwrapped with a shipping sticker on it. It was wedged into the front of the door and the bottom of the step so I had to go out the back door around the house and unwedge it. NOT A GOOD START. The GREAT ... The mat is a fantastic size very heavy and has very spiky barbs on the bottom (careful!) so it covers the whole area and does not slide around or creep anywhere. The MEH ... Despite the map being on low pile carpet it gets little sunken craters in it when I sit in one spot too long. The cratering happened within a week. I wish it was a bit more rigid. The problem is probably the fantastic rug padding under the low pile. In any case it's not bad but it could be better. So consider your rug thickness carefully.
I put down carpet tiles in my office and wanted to protect it from the in and out of the office chair. I bought this protector but with the carpet tiles being low profile/thin as compared to carpet the office chair kind of rolls rough over the mat. Probably wouldn't do that if it was over carpet but the thinness of the tiles make the rolling kinda bumpy. Not sure i'm taking it back yet and may trade for the smooth one.