This is the one that had started it all for me, that had left me wanting more Reacher stories the way only Child can write them. I read Persuader a couple of years ago and, as it was my first Reacher novel, I remember how intrigued I was by Child's style of writing. I loved the short powerful sentences, terse and crispy without any fluff. Add to this an intelligent giant with a fierce sense of fairness and you know you are in for quite a ride.
As for Persuader itself, it is Reacher at his hulking best. That is all you need to know, in my opinion.