Opinion Summarization research addresses how to help people in making appropriate decisions in an effective way. This paper aims to help users in their decision-making by providing them effective opinion presentation styles. We carried out two phases of experiments to systematically compare usefulness of different types of opinion summarization techniques. In the first crowd-sourced study, we recruited 46 turkers to generate high quality summary information. This first phase generated four styles of summaries: Tag Clouds, Aspect Oriented Sentiments, Paragraph Summary and Group Sample. In the follow-up second phase, 34 participants tested the four styles in a card sorting experiment. Each participant was given 32 cards with 8 per presentation styles and completed the task of grouping the cards into five categories in terms of the usefulness of the cards. Results indicated that participants preferred Aspect Oriented Sentiments the most and Tag cloud the least. Implications and hypotheses are discussed.