Some authors and publishers believe the settlement would give Google too broad of a license over their work. Even with the revenue-sharing system in place, many authors feel Google would be stealing some of their rights and question the effectiveness of an "opt-out" option planned as part of the settlement.

4. Google would have complete control over so-called "orphan works."

One area of concern is a type of book known as an "orphan work" -- a book for which the rights-holders are not known, or the author cannot been located. Critics say Google's Book Search deal would give Google an exclusive license and full control over these titles, allowing it to distribute and price them at its own discretion.

5. Other companies could be negatively impacted.

The settlement may have a negative effect on other book sellers and distributors, some worry, creating a mammoth system with which they won't be able to compete.