If you approach the book with an open mind it is not that hard of a read, the problem rises in the chapters dealing with logs, etc. Which essentially are good for background but not essential to understand. I and many others urged Phil to publish a BTZS "light" but in the end he declined because he felt a thorough understanding of the background is better to use the system to its outmost capabilities.
The actual concept of the system is so simple (like all great ideas) that sometimes it gets lost in all the information. In essence what you do is make a print of a step tablet and measure the ES (exposure scale) that the paper can represent, then make 5 or 6 contact negatives from a step tablet and develop them at different times. Mark the points in the negative that show the same SI (Scale index, what is normally known as contrast range in the ZS) as the ES of the paper and then you are assured to be able to repoduce the all information in the negative onto the paper.
Its brilliant, and I have to tell you that without this methodology, doing alt printing would cost 3 times as much and it would be a lot harder.
I am not saying this will produce "perfect" negatives that you just put on your easel and expose and you will have a master print. But I can assure you that the first test print will be damm close without having to go through all that test strip, contrast descisions normally made with the ZS. Some times you even get lucky and do get a print that comes out perfect on the first try!
Another great thing about the system is the information flow, if you calculate the average gardient, what Phil calls G bar, then anybody, even though they might have different times and temperatures can develop the film using your information to get similar results. For example if I develop my pd negs for a G bar of .8 at 75º for 11 minutes and another BTZS user wants to start making negs for pd all I have to tell him is do it for a G bar of .8 and he can go back and see his tests and adjust his developing so that, for example, he knows that in his system he can get a G bar of .8 by developing at 71º for 16 minutes.
Well, I will close this by saying that I feel like a fool having Phil's book for 10 years on my shelve and never giving it a chance. If I had I would have saved me a lot of agravation and wasted film.