The goal of behavioral economics was to prove that neoclassical economics, the current dominant paradigm taught at schools and used by mainstream economists, stand on completely erroneous assumption - that humans behave as perfectly rational agents.

It was never supposed to become the replacing paradigm. It doesn't have its own theory of how individual behaviour (microeconomics) composes into system behaviour (macroeconomics). But it showed that just summing up individual behaviour of independently and identically distributed individuals doesn't give you the macro picture that should tell us something about the real world either. It at best can describe a simulated game world, which only occassionally predicts something about our world.

Behavioral economics is de facto applied psychology and as such you'd obviously expect it to have study replication problems. Of course it will never be fully exact science as it tries to explain an evolving dynamic system of nonuniform units. Does it render it useless as the author points out? - unlikely.