On the first night, when I opened the book, it was 22:30. I stopped reading at 1:00. On the second and third night, the story repeated. Luckily, the weekend came and I managed to get back lost sleep.
When I say exciting I'm not joking: The main character gets a sudden promotion from IT manager to VP of IT Operations in a big company ($4 billion per year). What he doesn't know is that the whole IT organization is completely crippled and he got the job is to get it healthy again.
Having to manage severity one incidents, doing weekend long deployments, getting impossible constraints and requirements from business and security are just a few of the obstacles that he encounters in his new role.
Various IT problems keep on appearing in the first part of the book. After that, things start stabilizing and you are rewarded with a happy ending ;)

Although a work of fiction the book introduces various currently-used-in-IT concepts: kanban, the theory of constraints, DevOps, wait time is %busy divided by %idle, simian army, The 3 ways, the 4 types of work. People working in/with IT will appreciate the quick intro into DevOps and IT management. I doubt that non-techies will find the book interesting.
The idea that impressed me most was the comparison of the IT organization with a factory. Thinking back at my development experience, I observed that there are a lot more similarities between a factory worker and a software engineer than I'm comfortable to admit.

The main ideas are summarized at the end of the book. Along with them, you will also find the books (1, 2) that the authors used when building up the plot. I warmly recommend that you read at least this part of the book.

References
1) itrevolution.com/learn-more-about-concepts-in-phoenix-project/
2) itrevolution.com/resource-guide-for-the-phoenix-project-kanbans-part-2/