While the book is well-written and the ideas are well-expressed and thought out, Harris' theories just don't play well in a complex world filled with people. There is no set of rules or philosophies that one can apply to Christian premarital romance (nor any kind of romance, nor any kind of relationship, for that matter), and I believe that, unfortunately, Harris' ideas are a contribution to a philosophy that has caused much pain and cynicism in young single Christian circles (I can say this from experience).
In concurrence with Harris' ideas, many of our parents, with the best intentions, told us pubescent, hormonal Christians that we should wait for "God to bring the right one"; that "God has designed someone just for you". Harris has taken this idea and designed a dating paradigm that fosters to it, gearing up singles to pursue only that one, special, unique someone that God has made just for them. This has led many of us naive, unsuspecting singles to expect to suddenly wake up one morning with the perfect man/woman, a ring on our finger, passionate sex (that of course was saved for marriage without any sort of struggle), and a relationship with depth that's centered around Christ.
What I mean to say is, we know what we want and we expect God to get us there without any effort on our part. Having always been told to wait for God to bring this ominous "One" to us, to kiss dating goodbye, and that God has sculpted said "One" just for us, we have this hopelessly naive and incorrect idea that if we sit around, living our romance-free and happy lives (which, let's be honest, is unfortunately a bit of an oxymoron in our culture), God is going to make romance happen to us and another unsuspecting, beautiful, godly, pure individual.
The repercussions of this are the cause of constant frustration in both sexes. I've heard so many of my girl friends complain about this guy that they like so much, who they happen to know likes them, with whom she hangs out all the time (often one-on-one, over coffee) and this guy just won't ask her out, won't pursue her openly, won't lay his cards on the table and make himself vulnerable. Being a guy, and a guy that's been guilty of this, I can tell you that it's largely due to the aforementioned paradigm. Asking a girl out is terrifying, even if you know she'll say yes; vulnerability is petrifying. This is why the unconscious assumption that God will "bring the right person" to us is so comfortable. It requires no risk. God is going to do all the work for us. That's why we hang out with that girl we love for hours on end, always alluding to our feelings for her but never outright pursuing her, waiting for God to make it happen. It's comfortable, it's safe, and then you end up with mountains of sexual tension that haven't been expressed and eventually that coffee date becomes a make-out session without any pretext, without definitions, which leads to crossed boundaries and baggage. Fortunately I've been able to avoid this, but I've seen it far too many times for me to dismiss it as anything less than a pattern.
Alternately, I've heard many guys, myself included, complain about girls that simply will not say yes to a date. Because of our paradigm, those of us guys that have already gone through the frustrations of "kissing dating goodbye", realized that the difference between dating and Harris' ideas are simply in semantics, and have moved on to dating have found that many amazing, beautiful and godly girls will say no to a date with an amazing, godly man not because she's not attracted to him or not interested, but because she can't see herself marrying him. There's an expectation that, because God has this perfect man made for them, as soon as she sees him she'll be hopelessly in love and there won't even need to be a first date. A date, or courtship, or whatever you want to call it, is the context in which you get to know the other in order to determine whether you could marry that person. You can't determine that in day-to-day life. But, at the same time, girls expect us to pursue them, but not in a dating context because of the negative stigma given to that construct. Us guys are given so many mixed signals, because we're expected to pursue the girl like Christ pursues the Church (thanks, Francine Rivers, for giving every Christian woman the expectation that a good Christian man will be a cookie cut-out from Redeeming Love), but then again, if we do any kind of pursuing and the girl isn't already convinced that she could marry the guy, then we get shot down. So we are forced into the exact same context mentioned above, hanging out with the girl we like, allowing her to get to know us in a nonromantic context so that she can determine whether she could marry us (again, you can't determine how romantically compatible you are with someone in a nonromantic context). So as the two hang out more and more, and the girl still comes no closer to determining marriageability, emotions and sexual tension are still on the rise, and the same consequence mentioned above takes place.
All this being said, it's no wonder that young, single Christians are among the most romantically cynical beings I've ever met - and I am often guilty of this as well. I'm not saying that Joshua Harris is solely to blame, but I do believe that his books and ideology are a manifestation of this vague, misleading and tragic dating philosophy that is fostering so many embittered cynics in young Christian circles. The Church needs to begin addressing this issue, and realizing that there is no clean-cut solution and set of rules to apply to the grey area of romance. Only working relationship with us singles, intimate knowledge of our individual situations and, most importantly, the love and grace of Christ can lead us into romance with healthy expectations and practices. We don't need more books, we need older, experienced believers investing in us. That's what the Church is, anyway: a complex body of relationships, not a bookshelf of philosophies.