Want to see more cards from this set? Check out the dedicated blog at Grand Slam 1978! The intro post has plenty of production notes and its #5 post talks in detail about Hank Greenberg as a player and symbol.
UPDATE: Jack Wallin published a similar set of famous football players called Touchdown Club. Here's the #5, Mike Michalske. A near-set of signed cards sold for over $1700 in May 2011.
Value: This Hank cost me $6 on eBay in 2005, about right for a high-grade single. They're pretty hard to find, but demand isn't particularly high for the set as a whole.
Fakes / Reprints: As a collector-targeted issue, I doubt anyone reprinted these cards. Since the set specifically encourages signature hunting, however, be aware of faked autographs on real cards!