If you spend your time writing software or leading a team that creates software then this book is for you. Personally, I don't like the title 'Team Geek' because in my humble opinion, not all geeks are software programmers, and not all software programmers are "geeks" in the colloquial sense. If you ignore that bit, the book is full of practical, contemporary advice on how to work with a team.
Software is, despite appearances, a very human endeavor. From the outside, looking in, it may seem like software is built by typing code at your keyboard all day long. Arguably, typing actual code is a very small part of building and shipping a working product. Building software primarily involves effectively working with people from different domain and expertise. You could be talking to the customers or business analyst to understand the business domain and tease out the requirements. You could be working with architects, user experience team etc to come up with a high level design that underpins the development. You could be coding with or managing a team of coders, or you could be liaising with the test team responsible for QA. The pivot for all these activities is human interaction.
The crucial advice that keeps cropping up in this book in different shapes and form is that if you want to be a better software developer, architect, team leader you need to master the human element of software development. It is not a panacea but I would definitely recommend it to anyone who want to make themselves and their teams more effective.