From the programmer's perspective, there are quite a lot of things you can do with the Netscape Web Browser. These activities fall into two broad groups. The first thing you can do is extend the functionality of the browser. This normally means providing a Plug- In or defining new protocol handlers. The second thing you can do is to use the existing functionality of the browser in your own programs. This mostly means using DDE to control the browser, or using it as an OLE Server.
The book starts with a very brief outline of the Netscape APIs and a highly condensed introduction to OLE Automation and a chapter on how to create an Automation Controller Class. While these are both useful, I doubt that they would be enough if you have no previous experience of COM. You might need to get up to speed on COM/OLE/etc. first from another book before starting this one.
The real worth of this book lies in the remaining chapters, which are specifically about using the Netscape APIs. This starts with using the DDE Interface. The book gives a comprehensive summary of the DDE Topics supported by Netscape and gives some good examples of their use, such as using Netscape to resolve URLs, controlling the browser window position and size and logging sites visited.
The book then moves on to accessing Netscape through OLE, which allows you to access some of the browser's functionality from your own programs. Although this chapter is useful, I found it a bit thin. I think this is one area where the book could do with some beefing up. There is quite a good chapter on implementing Protocol Handlers and another specifically on interfacing to Lotus Notes. The later chapters in the book deal with how to extend Netscape by defining your own protocol handlers and custom MIME viewers.
I am a bit in two minds about this book. It gave a fairly good introduction to most aspects of programming with Netscape, but I frequently felt the want of more information. Given that there aren't a huge number of books on the topic, this is probably as good a place to start as any, but I don't think you will find it sufficient by itself. A good book, but not a great book.