I was disappointed that if I sit for more than a few minutes in any one spot the wheels on the chair create impressions deep enought that I then get stuck in them. It's very difficult to roll out of them when moving sometimes I have to get up and move the chair. The impressions do go away in a short time once the chair is moved. My other issue is that this mat would NOT stay in place which amazed me since it had 3 table legs on it (from an l-shaped configuration). So several times a day it would creep several inches under the table and I'd have to take the chair off of it and fight to pull it back into place. I had been afraid to drill it as it is hard plastic and I thought it might crack a lot. I finally figured my daily struggle with it was worse than some cracks so I took the chance. Once it was in place I drew around each of the 3 table legs with a sharpie then took the mat to the basement for drilling. I first drilled with a small bit in the center of each sharpie circle then used a 1 1/8" hole drill to accommodate the 1" round table legs. Worked like a charm no cracks and nice smooth edges. Now the table legs keep it securely in place.