But histograms do allow you to easily see one of the most important patterns to me, at least for technical books, which is that the book is excellent but too "hard" for some who aren't willing to put in the effort. Those books tend to have a lot of 5 star and 1 star ratings, with few in between. Check out the SICP reviews on Amazon for example. When augmented with a set of comments, it's usually easy to predict which of the two groups I'd be in.