It offers 256 given names used in the modern period (since 1750).
Patrick J. Stevens, selector for Jewish Studies, at Cornell University Library, wrote about the book:
The book, although not inexpensive, is highly worth recommending as a learned and deeply interesting reference source and discussion of Yiddish names, and by extension, of Ashkenazi Jewish naming practices and Yiddish historical linguistics. Chapters preceding the lexicon itself review not only the data fields for the names analyzed, but also the literature on the topic, the history of Yiddish ("Earliest Yiddish" appears to have arisen around 1000 CE) and Ashkenazi Jewish naming (contrasted with Sephardic practices).
According to Stevens, a World CAT search shows that it is available in 67 libraries.
It seems like it would be useful for genealogists researching their Ashkenazi roots, and the information contrasting Ashkenazi and Sephardi naming practices would be useful as well.
Keep an eye out for it.