When I first saw this tool I thought to myself, "why would I need this I can just free hand curves". Now that I own it I have completely changed my mind. The ruler helps you visualize what the curves will look like on the paper prior to making any cuts. This really help me from drawing a curve and errasing it because I don't like it or wasting paper because I don't like it once it is cut out. For us visual people, you can keep moving the ruler around until the curves look just right, them mark and cut. I sometimes like to cut the paper into a curved strips. Because the sides of the ruler are rigid you can make a pencil line on both side of the ruler giving you two lines to cut out the curved strip of paper.
I waited for a long time to get this little tool - it was always out of stock. When I did finally manage to get one, I wa super happy and pleased - even for the price. I am not great at freehand cutting or drawing so the fact that this bends however you want it to is great for me. I like the fact that it is longer than the paper as most rulers - being only 12 inches you can't always do what you would like. It's sturdy and made of a rubber/silicone substance that stands up to much use and abuse. I've also been able to wipe it off relatively easy with baby wipes. The case it comes in is also an easy place to store it. I was very happy once I got this. :)
This tool has just recently been added to my collection but I really like it. I have used it a lot more then I thought I would. It really holds shape. That was my biggest concern. I have seen in demos where people trace with a ruler then cut their traced line. I just use the exacto knife right along the ruler and have not had a problem at all. With either the ruler losing its shape or the cut not working.
What I would like to see in the future is maybe it being a big magnet so I could use it with my Basic Grey mat.