Spinellis and his co-editor Georgios Gousios have done a good job of selecting interesting essayists and of putting their works together into a collection that feels solid. Reading it will certainly make you think more about your own project's architecture.
In the Preface, the editors put forward a collections of Principles, Properties, and Structures for architecture. These would be a great way to index the contents of the book. Chapters 3-12 (covering Enterprise, Systems, and End User Applications) each begin with a table showing which of these principles, properties, and collections they touch on. Sadly, that's the extent of use to which they're put. I would have loved to have an appendix with a guide to which sections of which essays I could go to for more detail on 'Entropy Resistance', 'Buildability', or 'Dependency'.
Like most anthologies it has some chapters that different people will like or not. To me, some of the real winners are: Peter Goodliffe's "A Tale of Two Systems", Jim Blandy's "GNU EMACS", Till Adam and Mirko Boehm's "When the Bazaar Sets Out to Build Cathedrals". There's also plenty of meat for the OS or Enterprise level if that's where you'd rather read. Which chapters stood out to you?
Whether it's something you're building on the weekends or on the job, Beautiful Architecture will certainly do your code base good.