Well this is a welcome breath of fresh air into the dreary little world of development economics. 
 The contemporary debate over the questions of aid and poverty reduction have been restricted to two equally excitable schools - Jeffrey Sach's 'clinical economics', where he asserts that massive increases of aid are necessary across a broad spectrum of problems, and William Easterly's focus on locally-driven reforms. Easterly has a vicious criticism of Sachs, mocking its paternalistic tone and similarity to past colonial projects. To quote one of his more memorable phrases, he calls highly visible public aid projects the 'white band's burden', after Bono's publicity efforts in the early 2000s for Sudan. Another minor offshoot of this is the work of Dambisa Moyo, who argues that almost all aid should be cut off, except for purely technical advice on the restructuring of financial markets. Although both have some interesting proposals in their respective books, the public debate often devolves into meaningless polemic and abstract criticism. 
 What separates Banerjee from these new approaches is (gasp!) a compilation of statistical analyses on the effectiveness of aid, and bringing up new methods of behavioral economics in attempts to find the more irrational trends present in human behavior. To list a very simplified example - the very poor are often stressed by financial constraints. This leads to impulse spending, or attempts to make back payments on outstanding debts. 
 Another major target of criticism is the recent push for microfinance campaigns. Although they have been useful in some circumstances and have had a positive impact in the formation of local businesses, many of the loans go towards the payment of debts or for other needs which do not include entrepreneurship. Even worse, some of these microfinance institutions charge high interest rates and further worsen the borrower's financial situation. 
 Even though this book is rather disorganized at times, it has a great deal of compassion for the difficulties of the very poorest in the world, and the staggering difficulty in trying to alleviate their position. It is very difficult to offer any 'big solutions' to these contextual problems, and even the general guidelines and studies that the authors use could easily be misinterpreted for other situations. (It is important to note that very many of these studies take place in India, a very large place already. The scale of these conclusions is also problematic - Could studies which take place in one village work in another?) 
 But let's be fair. This is an attempt to present complex economic research to a willing public. For that, the authors deserve credit.