I don't intend to question Pollan's ability as a writer, nor do I care to check up on his interpretation of the history of hybrid roses or British garden design, but as a gardener who entered this endeavor from the ecologist/naturalist end of the spectrum, I found plenty of bones to pick with him.
A previous reviewer mentions Pollan's rant about The Nature Conservancy, which -- much to his chagrin -- declined to harvest, clean-up, or replant the trasured Cathedral Pines after they were damaged by a tornado. Pollan is clearly very comfortable with his position about how gardens fit along the spectrum between wilderness and human culture, but too often he relies on straw-men and oversimplified truisms to represent the views of those with whom he disagrees.
Examples abound, but some that galled me the most were his conclusions that: (1) the American environmental movement is too hung up about preserving Wilderness to care about the other 90+% of our lands (absurd! ever hear of the Clean Air and Clean Water Acts? the Endangered Species Act?); and (2) the moral and scientific bankruptcy of this philosophy has led to the 'degradation' of Yellowstone National Park, as exemplified by the forest fires of the late 1980's (or could this just be an example of the renewing power natural process, without the hand of human 'gardeners'?).
I accept that Pollan is a journalist and a (fine) writer, not a scientist, but a little more effort to gain an deeper understanding of both the science and the philosophies of those whose view differ from his would have been greatly appreciated.
Of course, it is Pollan's book, and a popular non-fiction, not an academic treatise, so some hand-waving to help justify his mostly-sensible views is his prerogative. I appreciated the humor and passion of Pollan's writing, and I am sure I would greatly enjoy a walk down his garden path.