This book, as Nicholas Carr has claimed about IT, "doesn't matter". As one reviewer stated, Carr is a good writer but should have kept his assertion to a short article.
Carr claims that IT (hardware and software technologies) is becoming a commodity and therefore that by itself it does not provide competitive advantage. This is eye-opening and insightful only if one believes all the claims of the dot-com era (some of which are still turning out to be true after all) and if one does not understand that the economy is getting more competitive all the time. So what? Isn't everything becoming commoditized? What is left after the Information Age and outsourcing of everything? Some say it is the Creative Age, in which creativity and innovation are what confer true advantage - human mental processes, some of which have to do with using or applying technology differently.
Carr readily admits good USE of IT does confer an advantage - but again, isn't this true with any input or tool? It is management and innovative use of the input rather than the input itself that confers some advantage.
One needs a much more sophisticated hands-on understanding of IT besides the superficial observation that hardware and software technologies are becoming commodities available to all -- besides, this argument is only true in a 30,000 foot view of the world.
When one looks closer, in most cases the "free" open source software that is theoretically available to all is not truly available to all because the expertise needed to use it is very limited. Can all organizations use Linux, Perl, MySQL, etc. equally well? If not, are they really "available to all", or only to those who can actually use them? That everyone can "buy" them does not equate with them being "commodity inputs" -- they are just "technologies" not actual "INPUTS" if they are bought and not used. These questions are intertwined and more complex than they at first seem. For better or worse, one needs an experiential, not an academic or theoretical understanding, of IT in order to arrive at an answer.
In the last chapter, Carr backs off somewhat, saying it is too early to tell the impact of IT - but if it is too early to tell the impact, how can he already conclude it doesn't matter? I suppose that is why he modified his title from the article title of "IT Doesn't Matter" to the book title of "Does IT Matter?". This question seems to be unanswered despite agreement that many information technologies (just as other technologies, products, inputs, processes, and so on) become commodities very quickly, and at an ever increasing rate.
Bottom line: you do not need to bother reading the book. If you wish to understand Carr's argument, read his original article.
As with so many popular "management books", Peter Drucker had already summed up what a manager should know and think about in a more concise way -- for example, that it is the "I" in "IT", not the "T", that matters. Organizations need INFORMATION not TECHNOLOGY and in particular INFORMATION about the OUTSIDE. For better guidance on strategy and IT, see Drucker's Management Challenges of the 21st Century.