My expectations: a profound book with insights on how mass collaboration changes "everything". Due to the high rating, I expected it worth reading.
What I got: a shallow, extremely (!) poorly structured book which touches an important trend. Some good (and thoroughly repeated) examples, even enlightening ones, many quotes type CEO-bla-bla. But the book suffers from too many repetitions and no real punchline. A balanced, critical discussion about the importance of wikinomics is absent, the authors seem totally in love with their creation "wikinomics" and loose their critical sense.
This book could and should be condensed to 20 pages (it's over 300 pages long!) without substantial loss of content.
All this being said: If you are interested in the web, "wikinomics", open source, and related trends, you are looking in the wrong place. There must be something better, but I do not yet know one yet. In a different book, "Hackers and Painters", by Paul Graham, there are a couple of pages where the author touches these topics: much more enlightening. Graham's book is brilliant, thoroughly readable, though technical in some chapters, and provides you with INSIGHT. It's not meant to touch the same topic as "Wikinomics", but the few pages where there is overlap are so much better...