Tom,
I'm using one in my new shop until I get my epoxy floor coating done. My son recently did a lot of work on his car, including changing out a transmission. There were plenty of spills on it, thats for sure.
As mentioned, it is just a piece of heavy vinyl, and like the ad says, it is very similar to a pool liner. It seems to work fine, but one thing that happens is when oil and fluids (other than plain water) are spilled on it, the vinyl will "pucker" or wrinkle up in the area of the spill. This happens if the fluid is allowed to sit on it for a length of time. If it is wiped up right away, no wrinkles. These seem to be permanent....not sure if I left the liner out in the driveway on a warm summer day that these wrinkles would disappear. There will also be wrinkle marks left where the tires rest. Other than that, it works real well. I don't think I will leave it down after I epoxy the floor, but as a protector for the bare concrete it works fine. I think if kept clean, especially under the vinyl so that a stone cannot pierce the vinyl, you should get a lot of use out of it. I also saw that they make an even heavier version. That may eliminate the "puckering" of the vinyl.
I'll attach a picture...right now I keep my streetrod engine on it, but you can see some of the discoloration and puckering on it from the tires.
Hope this helps,
Steve