In this paper, new schemas for feature categorization in different types of reviews, in the domain of books, are presented, so aspect extraction techniques could be later applied. We deal here with two different types of reviews: formal reviews about scholarly books, written by experts, and informal ones about fiction books, written by readers which are not necessarily highly qualified. Our final goal is to extract the most relevant aspects or features to which any opinion is expressed in these reviews, along with the sentiment associated, for later integrating it to book recommender systems, improving the quality of the recommendations. Throughout this paper, the need for different annotation schemas is proved, by developing a new review classification system, as well as making an analysis at lexical and semantic levels on both kinds of reviews, for finally concluding with the presentation of the new categorization schemas.