An interesting review of a very worthwhile book. Here are some more comments on the same book:

"It is not just the fascinating effect that makes the book special. It's also Flynn's style. There's an unusual combination of clarity, wit, apposite allusion, and farsightedness in making connections and exploring unexpected consequences. The Flynn effect, in Flynn's hands, makes a good, gripping, puzzling, and not-quite-finished story..."
--Ian Deary, Edinburgh University

"This book is a gold mine of pointers to interesting work, much of which was new to me. All of us who wrestle with the extraordinarily difficult questions about intelligence that Flynn discusses are in his debt.."
--Charles Murray, American Enterprise Institute & co-author of The Bell Curve

"This highly engaging, and very readable, book takes forward the Dickens/Flynn model of intelligence in the form of asking yet more provocative questions. . . A most unusual book, one that holds the reader's attention and leaves behind concepts and ideas that force us to rethink all sorts of issues.."
--Sir Michael Rutter, Kings College London

"Flynn provides the first satisfying explanation of the massive rise in IQ test scores. He avoids both the absurd conclusion that our great grandparents were all mentally retarded and the equally unsatisfactory suggestion that the rise has just been in performance on IQ tests without any wider implications.."
--N. J. Mackintosh, University of Cambridge

"Citing many scholarly works, Flynn paints a dynamic picture of what intelligence is and the role of a person's genetic background, physiology and neurology, immediate environment and broader social factors...he has produced an impressively multidimensional and often wise look at the elusive topic of human intelligence."
--Publisher's Weekly

"In What is Intelligence? James R. Flynn...suggests that we should not faciley equate IQ gains with intelligence gains. He says that it's necessary to 'dissect intelligence' into its component parts: 'solving mathematical problems, interpreteing the great works of literature, finding on the spot solutions, assimilating the scientific worldview, critical acumen and wisdom.' When this dissection is carried out, several paradoxes emerge, which Flynn in this engaging book attempts to reconcile."
--Richard Restak, American Scholar

"The 20th century saw the "Flynn Effect" - massive gains in IQ from one generation to another."
--Scientific American Mind

"In a brilliant interweaving of data and argument, Flynn calls into question fundamental assumptions about the nature of intelligence that have driven the field for the past century. There is something here for everyone to lose sleep over. His solution to the perplexing issues revolving around IQ gains over time will give the IQ Ayatollahs fits!."
--S. J. Ceci, Cornell University

"What Is Intelligence? is one of the best books I have read on intelligence-ever...This is a brilliant book because, first, it helps resolve paradoxes that, in the past, seemed not to lend themselves to any sensible solutions...one of the best things about the book is Flynn's sense of humility...this is a masterful book that will influence thinking about intelligence for many years to come. It is one of those few books for which one can truly say that it is must reading for anyone."
--Robert J. Sternberg, PsycCRITIQUES

"...In this thoughtful, well-written book, Flynn offers an account of why the so-called Flynn effect occurs and what it means (and does not mean)....This is the clearest, most engaging work on intelligence....All will learn from the author's nuanced arguments. Some may quibble with Flynn's observations, but their work is cut for them: one cannot fault his clarity or ingenuity. Essential."
--D.S. Dunn, Moravian College, CHOICE

"...James Flynn is best known for having discovered a stubborn fact...he established that in every country where consistent IQ tests have been given to large numbers of people over time, scores have been rising as far back as the records go, in some cases to the early 20th century. What Is Intelligence? is Flynn's attempt to explain this phenomenon, now known as the Flynn effect... an important take on what we have made of ourselves over the past few centuries and might yet make of ourselves in the future."
--Cosma Shalizi, Assistant Professor in the Statistics Department at Carnegie Mellon University and an external professor at the Santa Fe Institute, American Scientist

Link to description of the book (whence those reviews came):

http://www.amazon.com/What-Intelligence-Beyond-Flynn-Effect/...

An in-depth transcript of a lecture by the author:

http://www.psychometrics.sps.cam.ac.uk/page/109/beyond-the-f...