Crashnquilt,
The instructions that came with mine emphasize that you should use the eraser that comes with it. They say it's the only way to get it off.
I sure like it. I used it to mark some bias binding this morning and it makes very easy to see lines. We're taking a class at the shop where I bought it, tomorrow. I just might have to purchase a different color to add to this one. Think I'll get a green one.