I've had the chair mat for a week and it is flat on our carpeted floor and pretty much stays in place. Of course it gets dents from the chair. It's made from vinyl so I wouldn't expect it to be different. For the money and for light-medium use it's a good buy.
When I told the girl what I was looking for she went and got the mat cashed me out and even brought the mat to the car for me. I am handicap so that was a big help.
I wouldn't buy this again. It constantly moves since the spikes on bottom are so small. My chair wheels dent the vinyl and create grooves so it's difficult to move the chair.