It's about the concept of being able to leverage ones strengths. Not just strengths of muscle, intellect, or experience, but those talents that are things that come naturally, things that really make you light up and take joy in being who you are, or habits that are satisfying to simply do.
Rather than the old-school of "everyone can become perfect if they only fix what's bad/wrong with them", it's a new school of "everyone has a far better chance of success doing the things they love to do all the time". The perfection through "fixing" scheme means that everyone will be come mediocre at everything they hate doing, but be "well rounded". There's a lot of tremendous reasoning in the book about why this approach leads to self-hate, lose-lose scenarios, and a whole lot of frustration. It's embodied in our culture to look at what's wrong and try and fix it to get something right, rather than looking at what's excellent to make more of *that*. And it would be far more healthy and fun for everyone if they concentrated on strengths rather than weaknesses, first with themselves, and next with others. Not to say that one should ignore weaknesses, but how to deal with that's in the books.
jonsinger just wrote a mild treatise on why he thinks he's someone everyone loves to talk to, and I think he gets these same points dead on. What I've found different and unique and fascinating about his approach to people is that Jon's just excellent at sniffing out people's talents, what it is that they love, and he pursues, differently for each person, a conversation about the passion that fires up that person the most and, usually, he shares some measure of that passion so can speak to it knowledgeably. So, it seems a combination of Jon being fascinated by a wide variety of interests, in depth, AND being able to listen to someone well enough to figure out, on the spot, what fires theirs. Jon's points about going to someone else's home ground and his and his father's inquisitive natures speak to what I find fascinating about him and his approach to people.
The first book had this excellent thought experiment... remember that horrible relationship that was just the most gut-wrenching thing that ever failed? Yeah. That one. Sorry if it's hard to think about, it. But it wasn't that the other person didn't know you... it was that they knew you inside and out and then told you that it wasn't what they wanted? Or that they concentrated on your weaknesses and told you you had to change or do better? Or implied that you were lazy for not being able to easily do something they took for granted? That's what the whole "make yourself perfect by fixing your faults" syndrome is ALL about, and it sucks rocks compared to Jon's approach.
There's a lot to be said about being able to learn from everyone and one of the two books' approaches is that everyone is a hero with their own talents and true strengths. It brought tears to my eyes to hear about how world-class housekeepers for hotels speak of their job, of how it affects others and how perfection at their job brings them joy. It's not something I would ever have thought off the top of my head, but the whole concept rings true for me. That each individual can be powerful in an environment that speaks to their joys and uses something that they are the best at every day.