Over the past decades, research on online book reviews has inundated academic circles with numerous theoretical reflections and empirical manifestations aimed at explaining the effects of such resources on business performance. Yet, these studies succumbed to the conventional pitfall of assuming that consumers write reviews only after they fully read the book that they purchased. A recent industry report revealed that although many individuals initiate book reading, only a few finish them. With these considerations in mind, we investigated how consumers' book-consumption patterns affect their review behaviors and how reviews generated from incomplete consumption influence subsequent sales. We used expectation confirmation theory (ECT) as a theoretical foundation to elaborate on the review behaviors of consumers at various stages of their e-book consumption. On the basis of ECT, we argue that customers can submit reviews not necessarily after full consumption, but at any point during this trajectory, and even when consumption has yet to take place. Consumption patterns were traced and captured from records of reading activities on e-book devices and apps. Our results indicate that a considerable number of consumers provide positive reviews even before initiating reading or after progressing up to an extremely early section of a book. In addition, the relationship between review valence and completion rate can be characterized as a U-shaped pattern, given that reviews arising from negative disconfirmations occur more frequently than those emerging out of positive disconfirmations. The findings also uncover that customers occupying the extreme ends of the completion continuum provide less extreme review ratings. The effect of completion rate on review length is significantly positive. Our text-analysis results suggest that reviews based on sufficient consumption contain more useful insights than do those grounded in incomplete consumption. Moreover, review comments formed after incomplete consumption adversely affect subsequent sales. Finally, we discuss a number of our findings' implications and provide actionable recommendations that can aid platforms in their efforts to refine their online-review systems and policies in pursuit of enhanced credibility in peer evaluation.