That's a rare and valuable nickel, so definitely interesting! The toning enthusiasts would be all over this coin, particularly the registry set collectors.
What I find intriguing about the 1942-D over Horizontal D is that it provokes the question of "What really makes a rare coin valuable?". What I mean is, the D/hD isn't a particularly spectacular RPM. There are much more impressive varieties in the early
Jefferson nickels. I would even confidently say that there are many more impressive RPMs, although perhaps not as infrequently encountered. I can only assume that the tremendous price for this coin is based on registry sets, which in turn are based on the Cherrypicker's Guide. But it's a mystery to me why the registry set guys set the point value so high, and a bit of a mystery to me why Bill Fivaz and J.T. Stanton decided that this particular RPM was a cherry versus all the others they didn't include.
I think the sizzle of this coin is the value, but in all honesty, I would never swap it for a 1939 Doubled Monticello of equal market price. To my thinking, the 1942-D over Horizontal D nickel is the chocolate diamonds of the
Jefferson nickels varieties. Before the marketing hype made it a must-have, I bet collectors would have picked a host of other nickel varieties over this particular RPM.