Hooboy, what to say... Let me start by pointing out that the concepts and ideas that this book presents to the reader are pretty sound (... or should I say - SOLID?) and the writing style is what you'd expect from Uncle Bob: the words just flow, the language is simple, natural and clear and the wit sharp - all of it making the reading process a pleasurable affair. And the book is full of his sheer love for the profession and his geekiness and the trips down the memory lane of a battle-tested veteran who fought in the trenches of the early day computer booms and took part in shaping the best things of our present-day profession.
However, the way this book was envisioned has left me deeply dissatisfied and with a lingering feeling that it should never have been a book at all... Frankly, the more I think about it, the more I feel that a 30-40 page whitepaper would have been a far better format for the contents found within. My reasoning to be found below.
The initial 20-25% of the book is almost pure waffle and essentially just summarizes and grossly simplifies principles from Bob's other works and works of other renown programming professionals. It's all sound advice but my issue with presenting it here in this manner is that I can't imagine it being very useful or practical to readers that are unfamiliar with the concepts and it's frankly useless to readers that are familiar.
The next 20-25% is in part application of previously named principles and concepts on higher-level design and in part a list of prerequisites, dos and don'ts that a proper software architecture must satisfy - in essence a very slow intro into the clean architecture.
Finally, at page 200 the plot thickens, clean architecture is presented and it's a shocker! It's simple, effective and familiar - mostly because it's basically a specialized version of DDDLite employing a hexagonal/ports&adapters architecture. The architecture is elaborated on maybe 20 pages in total and then the remaining 150+ is a series of anecdotes and a whole lot of repetition of what's been said previously but phrased a bit differently and in slightly altered context. Yes, yes, repetitio est mater studiorum, someone's taken that quite literally.
Not uncommon occurrence are 90s teleshop-style bad practice examples, you know the type - picture a guy struggling to use a wrench in an obviously artificial and fake way, only to be presented with a solution to his problems. Some the examples used to illustrate the problems with traditional/mainstream architectures feels artificially exaggerated and blown out of proportion. A less extreme but a more lifelike example always wins. Additionally, Bob hasn't been doing much testing of, nor has he apparently worked with ORMs - in most ecosystems GUI testing is far from the bogeyman it once was and I can't remember if ORMs (at least the most popular Java ones) ever required you to break encapsulation and expose your object's innards to the world.
Also, were you expecting elaborate examples that go from high component level down to the classes? A real-world example complex enough to show all the intricacies and dilemmas you as a developer and an architect would be exposed to when adopting clean architecture yet simple enough to fit inside a book? Puny mortal, those are not for you! You can have examples marginally more complex than hello world apps accompanied by programming history lessons (which were fun but hardly educational).
To sum it all up - it's a pleasant read but the parts I enjoyed the most had nothing to do with software architecture and everything to do with who Uncle Bob is as a person, author and a software professional. If you want great and meaningful material on software architecture that advocates for more or less the same principles as The Clean Architecture, go read DDD by Eric Evans and then Implementing DDD by Vernon Vaughn - you'll be up for a 1000-page ride that actually teaches you something of practical value.