Fun.
These are fun because you get six different patterns in one pack, but if you want to create patterns on larger pieces of paper like 12x12 I would probably recommend to get a ruler instead. I don't know what they're called in English, but I have some metal rulers with patterns on the side that you can align on your 12"-paper and then just rip it against the ruler to create the pattern.
So, for smaller items like cards or so, these are fun! But on bigger items, like 12"-layouts I would recommend one of those ruler-thingys instead since they are easier to use on bigger things and also works faster since you won't have to align more than one time before you rip.