I bought this as a replacement for the previous one which cracked and failed after one year. I think the plastic dries out and then it's no good. But I needed it so I got another. One thing to beware of: the cleats on the bottom are VERY SHARP and will rip and tear your skin. Try to get someone to help you carry it. I was bleeding in several places after moving it.
The mat is exactly what I needed and is working well for me. In fact my daughter saw it and asked that I order one for her which I did. She is also very happy with hers.
The plastic does it's job in allowing you to move freely but the problem I noticed is if I sit too long in one position little divots form in the plastic and I am almost stuck in a pothole. It's the quality you get at the price you want to pay. That being said the plastic is not thin or flimsy so if you're more up and down than this might work for you.
So far so good. It is the right size for my desk and chair and seems to be well made. It came rolled-up (through UPS) so I had to lay the mat on the floor for two days (without using the mat) to flatten the mat but it is good now. I have had the mat for less than a week so I can't say anything about how long it will last but it seems ok.