Geoffrey Nunberg has a smart essay in The Chronicle of Higher Education on some of the limitations of Google Book Search. Plenty of people have groused about the problems they've encountered, but Nunberg gets to the heart of the problems by focusing on Google's shoddy treatment of "metadata":
I'm actually more optimistic than some of my colleagues who have criticized the settlement. Not that I'm counting on selfless public-spiritedness to motivate Google to invest the time and resources in getting this right. But I have the sense that a lot of the initial problems are due to Google's slightly clueless fumbling as it tried master a domain that turned out to be a lot more complex than the company first realized. It's clear that Google designed the system without giving much thought to the need for reliable metadata. In fact, Google's great achievement as a Web search engine was to demonstrate how easy it could be to locate useful information without attending to metadata or resorting to Yahoo-like schemes of classification. But books aren't simply vehicles for communicating information, and managing a vast library collection requires different skills, approaches, and data than those that enabled Google to dominate Web searching.
There's much to agree with there. I adore Google Books, and would have a hard time getting by without it, but they really have to devote more energy to these concerns. Here's hoping the high-profile finger-wagging will get Google to pay more attention to cataloguing.