I'd like to mention that despite OOP being in the title, I thought this book had a lot to teach that isn't specific to OOP architecture or OOP languages. Really, I think the star of the show is TDD and refactoring.

For a short intro to Sandi's style and approach, I always recommend this 35min talk: https://youtu.be/OMPfEXIlTVE?si=Ird6t8uDN86T06Y7

Aside from any specifically educational content, as a talk it is fantastic - funny, smart, well put together.