The kids thought this was amazing! I let them color all over my little ironing table and they erased it with the iron. Good 15 minutes of entertainment.
I did notice there was almost a clear haze left behind immediately after ironing that seemed to lessen after a few minutes so I'd be wary of using it to mark a quilt top but it would be great for marking on the back of squares you plan to use to make HSTs.
I paid about $4 for 2 of them so they're not too expensive. It's fun to play with too!