Each chapter has an introductory section, followed by the source of the functions. This is followed by a 'how to use it' section for each function, and a description of how the function works. The idea behind the split is that an application programmer can just use it without bothering about how it works, whilst a systems programmer is more likely to want the technical details. Both sections are well explained. An example of the use most functions is included, and these can be quite useful utilities on their own, such as a TSR for sending printer control codes.
Most chapters finish with suggestions for enhancements to the source code.
The source code presented is well commented and nicely structured. The code seems to handle errors well, with at least the most common eventualities catered for. Common problems, such as a 'snowing' effect that can occur on CGA screens, are dealt with and work-arounds given. Another appendix briefly describes the syntax and purpose of each function. I found the book very easy to get on with, and easy to understand.