This is a well-written book, yet terrible. It describes the arguments for liberalism well. But it is terrible because it does not manage to rise over the level of a propaganda piece. The analysis of populism makes interesting points, but it ultimately fails to explain why liberalism has waned and populists have become so successful in the last 20 or so years. The recipe for countering populism is basically just "more neoliberalism".
One reason for this failure is that the author seems incapable of entertaining the thought that liberal ideas, policies and government may have internal contradictions and unintended consequences that undermine it. The call for a revival of "classical liberalism" is entirely misguided. Reviving a corpse just produces a zombie. Any attempt at revivification of an ideology will inevitably transform it. Indeed, the "decent classical liberalism" Karlson advocates bears an uncanny similarity to social liberalism.
This book is a failure, and the fact that so many liberals seem to like it is a sign that liberals do not understand how bad the situation is. Being a liberal myself, I despair at our inability to face up to reality and reconsider our thinking in depth.