For many years, Stefan Grossman's blues materials have helped shine the light on the concepts and techniques used by the masters of country blues. All fingerpicking guitarists owe Mr. Grossman a debt for his efforts in preserving and teaching this vital style of music.
Delta Blues Guitar is a book that has been around for quite awhile, that is, it has stood the test of time. And the reason is that it is a valuable collection of solos by players like Charley Patton, Son House, Willie Brown, Robert Johnson, and others. The material is enjoyable to play and each piece is supplemented with informative notes by Grossman.
When I use this book with my students, we do not focus on merely learning the songs note-for-note and then quickly moving to another song. The written arrangements here are best seen as outlines that should be built upon with original ideas according to the ability of the student to do so. Therefore, this type of book is best suited to students and players who are not settling for the "note-for-note," "one-song-per-week" sort of approach to playing guitar.
In other words, after learning each tune, start filling it out with your own ideas. This can and should take a lifetime. That's how you play the blues, by endlessly experimenting, tweaking, adjusting, adding new ideas as you grow as a player. It doesn't have to be highly technical, in fact, a lot of great blues playing is actually pretty simple to pull off technically. It is the personal involvement and feeling that count the most.
I highly recommend this book to any guitar player who wants some fine arrangements and great, historic ideas on which to build an authentic repertoire of fingerpicking blues music.