Task systems are like musical instruments. Each person plays them differently. But you can learn so much from studying how they do so.
Joe Buhlig has built a working system that helps him integrate the various spheres of his personal and work lives. In Working with OmniFocus, he does a nice job of pulling back the curtains to show his day-to-day system of work.
The book is aimed at those who already have some understanding of GTD and OmniFocus. While he does review the various types of projects, contexts, and perspectives, it is likely most useful for those who are looking to continue developing their own systems.
Personally, I found his methods for creating and using Someday/Maybe lists, checklists, and templates as intriguing. I also plan to experiment more with Launch Center Pro based on his writings.
If you are looking for a concise overview of a working OmniFocus system, Joe Buhlig’s Working with OmniFocus is a solid resource.