I saw Francis' review of this book in the last issue of C Vu and thought I'd add my comments. First I agree with Francis that this is a short book and in part this is because there really isn't much to say.
There are 126 pages, not counting some reference tables and indexes, split into three sections. The first covers the RTF format. The book struggles in the sense that it quickly becomes clear that the format is not the most structured or even that rigorously adhered to by many applications. The way I used the book was to take some of the examples and slice and dice them to get what I wanted (and I suspect that's pretty much what most people will do). In this way I was able to generate some RTF reports for my application that could be rendered by the rich-text box component in .NET and in Microsoft Word.
The second section covers the generation of pretty basic Windows help files using a slightly modified RTF format. The final section provided some example applications, which demonstrate the concepts discussed in the first section. To be honest I'm not sure of the actual value of these last two sections. Help files are probably best produced using appropriate tools and the applications are fairly basic - but they do provide more examples to slice and dice.
That said, this is one of the few books out there for RTF. It is readable and has the advantage that you can read it very quickly, which makes a change these days. More importantly, you end up producing working RTF pretty quickly. Any weaknesses in the book seem more down to the subject matter than anything else.