I'll confess right off the bat - I cheated. That is to say, I'd read the book once before. Toby and I read it together 'cause it seemed like a good book that we should read, so we did. And it was good. Then we found out that all the care groups at church would be reading it, so we read it again. And it was better. I really benefitted by going through it in a more thoughtful manner and applying it to myself and my marriage, and asking questions like "Am I the worst sinner I know?" (yes, emphatically) and "How am I to model forgiveness?". While it is particularly geared toward married couples, I've seen very clearly how the principles apply to all relationships - love, forgiveness, examining my own heart in the matter, gently and lovingly reproving sin can and should factor into friendships and family relationships as well as marriage. It also helps that Dave Harvey (author) has a rather self-deprecating style of humor, willing to hold himself up as a model - usually of what not to do.
A phrase from early in the book to ponder: "Till sin be bitter, Christ cannot be sweet". Consider and discuss amongst yourselves...