Waldenstrom tries to dismantle what he calls Piketty and Co.'s outdated narrative about the evolution of inequality since the 19th century. He argues that we are today more equal than at any point in the past. However, there are several issues with this argument. For instance, the data he shows, more than disproving Piketty, show the same overall trend, thus enhancing the "outdated" narrative.
One strong point of the book is its policy orientation, something that economic historians often forget. I should say that, in general, the policy recommendations are sound: enact policies that enhance house ownership, promote access to financial instruments, invest in public pensions, opt for capital rather than wealth taxes, etc.
Waldenstrom argues that wealth democratization via pension funds and home ownership produced the great leveling of the 20th century, not wars and taxes. Economic growth, he claims, is the great leveling source. However, he fails to recognize that not all growth episodes achieve equalization, thus making generalizations that do not match empirical research. He claims that education, healthcare, and infrastructure are the real heroes. However, those things require public investment, thus financing tax revenues. In my opinion, this sloppiness in the arguments works against the author's goal in his crusade to promote a new narrative.
It is a good book, but it punches below its weight.