This book is from 2010; 10 years is a long time in the software industry. I hesitated to read this book, being afraid it would be completely outdated.
Two things;
1. The tools used did change. Today's monitoring solutions have different names. Still, the logic of tracking application behavior and especially the system as experienced by the user, is of utmost importance for today's web operations.
2. Tools may have changed, but not the way devs and ops behave. (Especially during an outage.) The postmortem and war stories, being about an outage, a system scaling up, or how to choose the metrics to monitor are lessons you can learn without having to pay the price of making the mistakes done and graciously shared in the book.
Also, it's a fast read, and it's easy to spot the chapters which are likely to be outdated/less relevant given today's tools. I highly recommend chapter 13 on post mortems and chapter 11 on "How your users feel: user-facing metrics" for their eyes-opening potential. (as an engineer, it's easy to focus on CPU usage, I/O, etc. where the actual value of monitoring is knowing whether your service delivers as expected to the final user.)
A 4.5/5