I love the Head First series, I've read some books and all of them are really great at storytelling and explaining concepts easily. Even tho I've read this book online, still, it's a very good explanation.
Overall, the book is on the basics of software architecture. Nothing unusual or something I didn't know, really basics.
Architectural characteristics, decisions, logical parts, and tradeoffs. Everything is a tradeoff, right? I enjoyed examples and recalled ADR and other useful techniques. I recommend this book to everyone who just starting on architecture. Along with something on DDD.