We did this book over the course of the last eight months or so in our community group (a month a lesson rather than a week or two a lesson). I took a long vacation right in the middle, and missed a bunch of it, so I went back and read the whole book from the beginning.
This is an excellent book on missional living, how we as Christians should live to bless the city and those in it rather than withdrawing, or becoming a part of the culture. Tim Keller takes as his principal text Jeremiah 29:4-14.
He starts out with having us take a look at our hearts, and the idols in our lives that may prevent us from being the light of Christ in the lives of those around us, and even how those around us may feel because of how the idols in our lives make us act. Very convicting.
I appreciated his definition of shalom, "total flourishing in absolutely every dimension: physically, relationally, socially, and spiritually." I also appreciated his discussion of work, and sabbath rest. That was also convicting.
At the end, there is a questionnaire that Keller encourages us to fill out annually, that is a heart check on how our Gospel living has impacted our idols, and how we relate to our community and the world over the last year.