Bought myself one of these last year. The D,Line one is cheaper than BakerySugarcraft brand and sugarcraft's isn't heat resistant.
I'd always had a problem with getting my cookie dough or pastry catching in imperfections on my bench. The mat ensures a relatively flat surface (no guarentee you got no crumbs beneath it!) and as you can flip up the edge you can protect your surface from sink splashes really easy. The size guide is really handy if you know what size you need, and it has rough measurements along the edge too – inches along one edge, cm on another. I get problems with storage and drying though. I wash it after use, but its floppy so it's not easy to dry it with a tea towel. I usually drape it over the dishes in the drying rack, but if weather's good and wind low I've sometimes pegged it on the line! Storage would be best rolled up down the side of a shelf. Mine's rolled in its original bag in the utensil drawer, not ideal but out of the way.

I use this every time I need to put scones, pastry, biscuits or any food stuff out to be flattened, rolled, etc. The mat is easily cut, so a blunt knife that doesn't go through the silicone is ideal. The biggest advantage is that it can be washed easily after using and is sterile and takes up little room rolled up in the cupboard. I love it. This is the second mat I have had. The last one got cut with sharp knives!

Would recommend however be aware that it can discolour and stain