Cooper's C# Design Patterns is a cookbook of solutions to design problems, using Visual C#.NET. Knowing your informational requirement, you would want to find the recipe quickly, and the instructions to be clear. Cooper's book isn't easily used as a catalogue of design solutions.
Although the index of the book says otherwise, I find the book to be in three parts. Part I is an excellent one hundred page C# summary and reference. Part II is about constructing user interfaces, using the .NET Framework. Part III is more about design issues per se. By starting off with an introduction to the C# language, Cooper targets his book at C# novices.
Parts II and III of the book consist of chapters per design pattern, and one example or more, plus its code, per chapter. Much of the text in the chapters is about the examples used. All the example code is on the accompanying CD. Snippets of it are repeated in the chapters, and are discussed atthe level of code lines. The reader must shuttle back and forth between the book and the CD code. However much novices will learn by searching through the example code, this book could do with less elaborate examples that more readily and effectively convey the design principles. Although Cooper has an intelligent and pleasant style of writing, Parts II and II of his book cannot be readily used for reference. The design patterns are not presented in a way that allows the reader to quickly identify a solution to a particular design problem.
If you were to buy the book just for its C# summary and reference, that alone would be money well spent. As to the rest of the book, it is Visual C#.NET oriented and not just about C#, as the title suggests. The reader might want to study the book in sufficient detail to be able to write a top level overview and, after finding a match between a particular design query and a design pattern in the book, continue to study the relevant chapter in further detail. Sitting down and reading the book from cover to cover is not what I would suggest, but who would do that with any cookbook?