This is an amazing book that improved my effectiveness as an engineer by an undefinable amount. Instead of just randomly picking components for a cloud application, I learned that I could pick the right tools for the job. This book does a really good job communicating the trade-offs between different designs and tools.
I have always wondered "what next" after having read data-intensive. Some suggested looking at research publications by Google, Facebook, and Microsoft. What do others interested in the field read?