We also have a rhino cutting mat - been using it for nearly a year and it's holding up well so far. We try to use just an x-acto knife on it, since it doesn't cut as heavy as a standard utility knife does. At this rate, it should last a few years before we have to flip it over and start on the other side.
We also put the square grid underneath the mat - it's a handy tool to line things up and check for square.