My assumption is that you are an intermediate or advanced Visual Basic developer working with or anticipating VB .NET. This book is also very suitable for students taking advanced programming courses and recent graduates looking for a real-world understanding of debugging. Both team leaders and nontechnical managers should find it valuable for gaining an understanding of the reliability and performance problems faced by their developers working in the trenches.
This book also assumes that you have some prior knowledge and understanding of the VB .NET language, the CLR, and the .NET Framework. It isn't suitable as an introductory text for these subjects. Though I often discuss the subtleties of a specific feature and how you might (and might not) want to use it, you should read the documentation extensively and experiment in order to learn the feature being discussed. Although it would be marvelous to be able to provide computer science “level introductions to every subject, this would have resulted in a book at least three times this book's current size ! So instead, the emphasis is on problem avoidance and debugging, with feature introductions that are relatively brief and only expanded where it's essential to the plot.
My final assumption is that you believe developers are responsible for fixing their own bugs, preferably before they reach the testers and certainly before they reach production. If you think that testers or end users should be the ones to find some of your bugs , then hopefully this book will change your mind or at least expose you to a very different viewpoint.