While visually I really like the design, in terms of usability I'm not entirely sold on it. Book covers can be hard to read (for both the title and the author) and there can be many different cover designs which people may not recognise. I would strongly suggest adding adding the title and author as static text that you can see at all times.

One other point, I don't think the disparity between positive and negative cloud icons is big enough. On Rotten Tomatoes it's crystal clear.

Love the site concept. Have been looking for a site like this for ages. Looking forward to seeing it grow.