I read this book many, many years ago (probably when I was in high school at the time... 2000-2004 era or so), and found it really heavy and inaccessible at the time. I picked it up a few weeks ago and started my way through it. Lately I had been feeling really convicted over the "lax" approach I had had for many years on sexual purity/lust/etc. Take your pick, really.
Steve Gallagher outlines many, many solid truths in this book. I found his portrayal of sexual sin especially and its consequences really eye-opening -- both in the Scripture he uses to back up his claims, and in the real-life stories of utter destruction he's encountered through counseling at Pure Life Ministries. Much of the book focuses on explaining the spiral downward into sexual sin (and addiction), and how that affects nearly every aspect of a person's life. It's pretty amazing, how he identifies all of it, and he's spot-on in so much of it.
I wish he would have spent a few more chapters on practical application for battling sexual temptation and sin, and so on (only about 3-4 chapters out of 17 are dedicated to this), so I would consider this book, as whole, more of a deep-dive into the NATURE of sexual sin... though not necessarily an absolute guidebook for combating it. That said, the book stands powerfully on its own, and if you had only read one over the years on the subject, you would be well off even so.
There were a couple things I didn't agree with so much in the book. First, in the opening, pages, Steve cites a few "current events" type stories of college students essentially participating in pornographic live demonstrations in their health classes, along with demonstrations of various sex acts, all within moderately well-renowned college campuses. The footnote stated the story having appeared on a website in 2001-2002, so I tried to pull up the site myself to see if it was true. It seemed so outlandish, so I figured I'd check the facts myself. The sites he was referencing were admittedly very conservative whistleblower-type websites that, while I don't inherently have any issue with, failed to cite any sort of news release, press detail, or interviews with anyone in particular. It was honestly as if the original website could have made up the story from thin air, and published it as fact. I don't fault Steve for this, but I was disappointed that he would quote a source that failed to back up their claims with hard evidence.
Steve also spent a moderate amount of time (a full chapter) on the influence of demonic forces in a person's life driving him to sin. Now... I am not discounting the reality of a spiritual realm by any means. But his level of focus on this aspect seemed, as an afterthought, really forced to try to spin another (seemingly outlandish) cause for sexual sin in a person's life. I come from a very traditional background, church-wise, so I suppose that's to blame for my hesitation as well. He doesn't go so far as to suggest demonic possession in a person's life for sexual sin/idolatry, but he comes close. It just caught me off-guard and rubbed me the wrong way. This section, I found, also lacked the level of Scriptural basis and references he had normally included in other chapters.
Other than those two "gripes", it really was a very good book. For someone really lost in a lifestyle of depraved sexual sin, this is a really powerful book. At any level, really, it's a powerful book. But like Sam (another reviewer, previously) sad, there are many other books out there that focus less on the nature of the sin, the stories of depravity, and so on, and instead focus on freedom, grace, and the Truth that sets us free from ALL sin and death -- not just sexual idolatry (Randy Alcorn's "The Purity Principle" and Josh Harris' "Sex Isn't the Problem: Lust Is" both come to mind).
Regardless, I hope this helps you in your decision to read/not read this book. It was certainly insightful for me, and I am very glad I re-read it all these years later. I just wouldn't probably use it as the ONLY foray into the subject.