IPA Researchers in Superfreakonomics

Research on charitable giving by IPA President Dean Karlan and Research Affiliate John List is mentioned in Ian Ayres' review of the new Superfreakonomics

Randomized field trials get a shout out as well, since Ayres writes that all regressions wish they could be based on randomized experiments:

There is a new zeitgeist in the way economists think about running regressions. Today, statistical economists explicitly think of their regressions in terms of randomized experiments. They think of the variable of interest as the "treatment" and ask themselves what kind of assumptions they need to make or what kind of statistical procedures they need to run on the historic data to emulate a randomized study.

Has anyone read Superfreakonomics yet? I'm curious especially to hear a randomista's opinion on the field experiments chosen and how they're presented.