The book is fine as long as you want to use the God-Machine and have the contagion be an error/problem with the mod machine. If you want anything else the book isn't particularly useful. Honestly it just feels a little uninspired. All of the sample crossover chronicles have different effects on the world but they all come from the same source the God-Machine. It would have been nice to see some examples that had a different source or cause. I can't say the book is a bad one it's just unfortunatly only useful if you want one certain thing a God-Machine chronicle.