Some readers might be disappointed that Nancy Snow's book doesn't provide a complete account of virtue. We are never told exactly what aspects of social intelligence counts as virtues since vices are also grounded in social intelligence.
What this book does do quite well is show how a philosophically viable account of virtue ethics could be made consistent with the available empirical evidence. Situationism, which denies that there are any "global" character traits that could could as virtues, overlooks ways to interpret the evidence in ways consistent with the existence of virtues. Snow's interpretations, I think, are quite plausible and far more in keeping with common sense than those of the situationists.
The points in this book are well made, but I came hoping to find a complete account of virtues here. For that, we may need to wait for a follow-up.