I participated in one, and the end result wasn't a quilt top I would have chosen to make. I suggest you either do as suggested previously, and just collect the steps, so you can decide at the end if you want to make the top or not. If you'd rather make the top as the steps are revealed, for the surprise/fun part of it, I'd suggest first researching the designer's past mystery projects to see if you like those. Usually there are photos available of their past mystery quilt project results. That way you can get a fair idea of whether or not you tend to like that particular host's choices.