An interesting book, which makes a moderately successful attempt to teach advanced level Basic. Unfortunately, it doesn't go far enough and, as a result, some of Mr. Cuellar's programs are less than satisfactory.
I think a diligent reader who typed in all the listings would have more questions than answers at the end.
In the introduction the author claims it is possible to program almost any task in Basic, provided you don't mind how slowly it runs.
For example, he demonstrates a technique for making the filenames found in the disk catalog available to a program. Oddly, this is quite hard to do in Applesoft, so this technique could be very handy. However, when examining the code, I found that he is calling DOS to do a normal CATALOG, then PEEKing into the screen memory and reading each character from the screen itself.
Perfectly valid, but with the disadvantage that it uses up the whole scree - and may well destroy carefully designed layouts!
It's not all bad and at times very good... I particularly liked his handling of how to implement a recursive subroutine in Basic, and the section on sorting and sort routines was better than most that I've seen.
Overall, worth a good look, but not a final definition of what is practical in Applesoft.