We bought the Xtreme cutting mat a few months back and so far we like it fairly well. It's very much well worth the price. We got the 4'x8' mat and although the last 8 inches or so have a slight curl, it mostly lays flat. It holds cut marks pretty bad and you can feel them so I would guess these things are made as an economical, temporary solution. We may get 10 or more years out of the thing, but I really doubt it.
I would prefer a self healing green mat but it's just not in our budget at the moment. But I can say I've had my 24"x 18" self healing mat for probably at least ten years now and I swear the thing will never wear out and I've never even flipped it to use the back side yet. I was cutting stuff on it long before I ever got into the sign trade. It's literally covered with thousands of cut marks and it's still perfectly smooth and flat, something you won't quite get from Xtreme mat unless you use very slight pressure and a very sharp blade, but they state that clearly in their disclaimer, basically that it isn't self healing.