Gladwell writes well, but I agree with one reviewer who says that he doesn't provide any information about how to successfully talk to strangers (which would have been useful). Also, in my mind, he doesn't even fully flesh out what a "stranger" actually is. The young black woman stopped in a misguided police effort to search for guns and drugs in any car they could stop for any reason does not seem to be a "stranger" in the way Montezuma was to the arriving Cortes.
The book seems a bit unfocused or maybe multi-focussed to me. The research on deception and how badly we can identify liars was interesting, as was the importance of congruence between our behaviour and emotions, and how people expect us to act in a given set of circumstances.
His storytelling is skilled, and much that he had to say is compelling, but I'm left with an unsatisfied feeling that the whole doesn't hang together in an intellectually satisfying way.