I love my Shape Cut -- it really helps get things "squared up." I notice that when I use it a lot (with my 45mm rotary cutter) I do have to change the blade more frequently. Also, it really helps to guide your rotary cutter in the slots if you hold the rotary blade at closer to a 90degree angle. Trying to roll through the slots with the handle more horizontal (almost parallel to the mat) puts the blade in contact with the plastic more than holding it almost straight up. This has been my experience but I'm interested in what others have found.