I may have read just too much of similar themed texts recently. Crabbe's Busy seem utterly un-original. There is the usual mix of second hand research reporting and personal anecdotes to fill the gaps in support of an argument.
The list of references is impressive, admitted. Yet, mixing articles from highly respected authors in highly respected academic journals with pop-science books is less than inspiring confidence. The reliance on personal anecdotes adds to that impression.
On the other hand, the book's thesis seems to be pretty much common wisdom nowadays. Many of the cited articles are ten or twenty years old. And thus, the gaps in the support of an argument may be not important at all. The conclusions are all accepted, there is nothing controversial.
This still leaves the entertainment value of the book. It reads quite nicely.