This is one of the books I've been meaning to read for years. My first teen is nearly 15 and I've finally gotten around to reading it. I have a great deal of appreciation for the five love languages as presented by Dr. Gary Chapman. Randy and I have explored this from both a marriage point-of-view and from a parenting point-of-view as we've taught a couple of parenting classes at our church in the past few years. I think the whole concept if phenomenal and can effect a positive life-change in relationships of all sorts, from marriage to parenting to friendships.
Being quite familiar with the five love languages, I admit I skimmed a great deal; however, I'd recommend taking notes and taking your time on this if the concept is relatively new. I am surprised that Dr. Chapman doesn't include a "test" to see what your/your teen's love language is. I found several online. This one and this one are abbreviated on-line versions of the test. At this site, you can download the extended tests, here called TouchPoints of Love (one is for adults and one for children). If you've never done this with your spouse or your kids, I'd highly recommend it. You may confirm what you always knew ("My son loves gifts!") or you might be surprised. I always assumed my primary love language was words of encouragement, but I was wrong.
On a personal level, I alternated between two main emotions while reading this book: sheer terror at the awesome responsibility of being a parent and parenting a teen (with more to come), and relief/consolation that we seem to be doing a lot of things OK. Basically, I went between, "Oh no! We messed up!" and "Oh good! We do that!" I have made it a habit to read parenting books once-a-year or so. Even if much of the information is repetitive, just the reminders serve us well and force me reevaluate how I'm parenting. I think this is about the best book for parenting teens that I've read. Come to think about it, I think it's the only one; but I've read a lot of parenting books and this ranks right up there with the best!