He is a man that is primarily a fantastic Jazz pianist that has expanded his performances to playing guitar and ukulele as well. Glen is an advocate of playing the ukulele with a low 4th string. (I have both high and low G concert ukuleles.) Glen is a rare individual that can put his knowledge in a concise, low-technical manner which means his tutorials and books get you going quickly.
Glen's work focuses on Jazz and how to get jazzier sounding music out of your ukulele. The Jazz Blues book is relatively thin, 25 pages according to my count. But the book starts with understanding what makes jazz and what blues are in a very tidy several paragraphs. If you haven't played many 9th's or 13th's type chords -- you're in for a surprise at their ease of play and great sound. Glen works with barred chords which every teacher discusses but few students explore -- this book gives very comfortable barred chords to work with.
You may feel a bit out of sorts to begin, but by the end of the book you'll be playing Jazzy Blues totally in 9th's & 13th's with slides, walkdowns and turnarounds. I have each of Glen's books from classes that I've attended. If your interested in trying Jazz or Jazz Blues, Glen creates great introductory books at reasonable prices.