I agree. A first step is to search HN for "book review"[1] and see what the review says and how many upvote it has. I know it's not exactly what you ask for but it's a start.
[1] https://encrypted.google.com/search?q=site%3Anews.ycombinato...
[1] https://encrypted.google.com/search?q=site%3Anews.ycombinato...
Edit: I do still think an up/down vote system to build a Top Hacker News suggested books, could be really cool to see