I have the 2nd edition of this book in my numismatic library and highly recommend it for anyone interested in collecting the medals known as So-Called Dollars (SCD).
The second edition contains a reprint of the entire 'Introduction to the First Edition' language which originally appeared in Hibler-Kappen classic 1963 volume. That provides a nice foundation for the purpose of the cataloging and the criteria for what is included.
It was this criteria GR58 that led to my comments on your other post on the 1933 Chicago fair medal ... it is not a SCD for those reasons.
The second edition also contains what I believe are some significant enhancements for the modern SCD collectors ... most notable updated rarity information based on the best knowledge available in 2007, and an updated listing of SCD that were missed in the original edition.
Concur with commems wise comments that the majority of the updated listings are simply 'new' composition strikes that had been recognized between the publish dates of the two additions ... but there are also some significant issues that were unknown to Hibler-Kappen in 1963 that appear as well.
As an example of the latter ... from my personal interest in the SCD issued for the 1915 Panama Pacific International Exposition ... HK-410b (Kentucky Exposition Fund) did not appear in the 1963 edition due to it's rarity that Hibler-Kappen likely never knew of it's existence. Today there are a total of 5 certified examples graded between NCG and PCGS.
This age old wisdom always applies ... 'buy the book before the coin'.
If your are interested in SCD ... spend the $40 or so on the 2nd edition.
David
Take a look at my other hobby ...
http://www.jk-dk.art