My grandmother gave me this skillet today. It's not my first cast iron (i have a mid 40s Lodge), but it is my first Griswold. It definitely needs stripped and re-seasoned, but looks to be in pretty fair shape.
It's a small logo #8, but I found this interesting in the FAQ:
"One of Griswold's most prolific pieces is the No.8 block TM smooth bottom skillet. For these Steve Stephens, a long time collector, has identified all letters of the alphabet (plus no letter), except for the letters I, O, U and Q and some of these could still turn up. "
My skillet definitely is stamped with an I. I know that doesn't mean it's rare or extra valuable, but I do think it's neat that I happened into one that seems to have a rare/uncommon letter.