The problem with Google Books is search capability within "your library" really has no way to constrain itself to tables of contents and/or indices; even advanced search falls flat on its face by this measure and generally sucks hind tit by every other. I'm just imagining running a search query for "recursion" only to have Hofstadter and Wolfram comprise 90%+ of the return.
Even if full search capability is what you really want, you're limited to ebooks for which digital rights are established via Google Play purchase. For everything else that isn't acknowledged public domain, you'll get a tease preview without even a hint of completeness...if you get anything at all. Invested in a Kindle digital library? I'm liable to suspect Google gave users vested in Amazon DRM a gratuitous GTFO-not-in-my-backyard finger.
Then there's the issue of specific revisions, e.g. it doesn't matter that Google Books shows skant preview of 4e Sedra/Smith when 5e is on my bookshelf--which, oh by the way, doesn't have preview.
Then there's the issue of copyright lockdown, e.g. only one of Carroll Smith's popular ...to Win series has any preview; the others are on lockdown. Same with Milliken on vehicle dynamics, Katz on aerodynamics, and many other titles published by SAE.
(Observe how the thematic high mark we've been striving for is a mere preview.)
Which brings up the issue of availability, e.g. good lucking trying to find the Institute of Navigation's canonical GPS red books in a Google Books query, or specific translations of the Bhagavad Gita, or other rare publications that an archivist would generally not hesitate to shoot you dead if caught attempting to adulterate in a scanner.
Surely I'm not the only person on HN who maintains a tangible library that's 1000+ large and growing. Like the author, I care about what's in my library, not what Google Books superficially pretends to offer as a front to getting me to purchase books in the digital (when available) that I've already paid handsomely for. Amazon and eBay combined see roughly 70% of my bookshelves. Even if Google Books did a fair job by some objective measure, I neither need nor desire their service.
