How well I remember my first discovery of this book in the 50's .
The first main 'revelation to me was that instead of playing major 7ths and 6ths with the notes in order on the 1st string,Baker shows how to play them on the 4th string.
Also he shows that you only need 4 note chords in order to produce a more sophisticated sound,by not duplicating notes.
He also shows examples of suspensions of added 9ths to the basic chords.You here lots of this from Barney Kessel with Julie London.
I reckon that those 2 pages alone are what changed my playing.The crux is that the 4th string carries the moving voices for voice leading.
It is a short step from this to playing 3 note chords like Freddie Greene
Of course in 50 years, jazz guitar and its players are doing things unheard of in those days (see Martin Taylor,Ted Greene,Tuck Andress,Lenny Breau etc.)
But if you are a new jazz player,this is a great way to start.I could apply the chord info easily,but I have a good ear.
There are many books out there now,many excellent,but I feel to get started this is a book that you can dip into,and out of even if it isn't the intention of the author.
There is absolutely nothing here to intimidate anyone,,,,so buy it and learn the first page of chords and do the exercises if you need to.Happy playing.