I purchased this my second chair mat. They do last quite a long while. They are a bit harder than I originally thought but my desk chair moves effortlessly as I change positions at my desk. If you're so inclined to purchase one make sure you pay attention to the label attached to the mat: some are made for hardwood others for different types of carpet pile. The right style for the carpet you have on your floor will make a difference in the wear factor. I also believe the wheels affixed to your chair legs will affect the lifespan. The harder wheels will definitely wear the mat faster.
I bought this for my wife to use at her desk at home. It is just the perfect size--not too big and not too small. We have medium pile carpet and this chair mat seems to work great with it. It certainly will protect the carpet from wearing as the desk chair rolls around on it.
If there was a zero star rating for this I would use it. It's a very badly made product. I used it for a week and it had several cracks and huge punctures in it. I returned it. DO NOT BUY THIS CHAIRMAT.
My old chair mat got so brittle with age that it broke apart and the chair wheels were getting stuck in the holes so this one is a nice change for me. It seems to be thick enough and keeps its position on the carpet without moving around. I wish it were a little bigger but I did not want to pay what the bigger ones cost. I like that it's clear because you can see the carpet color underneath and the mat isn't so noticeable. I've read reviews of cheap chair mats where the customers complain that they're so thin the chair dents deep into the mat and makes it hard to roll the chair around. I don't have that problem with this mat. It dents in slightly which isn't a problem.