This book is a must-read for any developer who is building or consuming .NET libraries. Even if you are familiar with the guidelines (from blogs, FxCop, or elsewhere) this book is outstanding--the authors sprinkle the primary guidelines content with commentary from other bigwigs, including Jeffrey Richter, Rico Mariani, Anders Hejlsberg and more. Through their comments, you get the "story-behind-the-story" (which guidelines are really important, which guidelines they disagree with, which guidelines are not followed the .NET Framework itself, etc.) This adds valuable practical advice, and makes for an interesting read.