I don't have one, but was thinking the other day as I was doing some hand piecing that one would be nice. My girls all had one when they were little, they loved to draw and color and it was great for them.
I'm thinking one would be nice for me now. If I remember correctly the size was about 12" x 18". If I were to have my DH make mine I would want fabric on the solid surface as well to help hold onto the fabric that would be laying on it!