For me it is difficult to give a proper rating or review here, because it is difficult to say something about this book. I originally read [b: Software Architecture: The Hard Parts: Modern Tradeoff Analysis for Distributed Architectures|58153482|Software Architecture The Hard Parts Modern Tradeoff Analysis for Distributed Architectures|Neal Ford|https://i.gr-assets.com/images/S/compressed.photo.goodreads.com/books/1625600270l/58153482._SX50_.jpg|91153038] and there were many mentions of this book inside of it and the title of it is really intriguing. And it is a good read, but basically summarises lots of the information that is in the other book and doesn't give much details and examples how a fitness function can be. There is more like a loose description what can tested and what should be.