One thing I have learned from Yelp and other online review sites is there are two kinds of people: Those who consider expected mediocrity as 5 stars and those who use the entire rating system. The former rate a greasy spoon 5 stars if their hot slop was not thrown in their face. The latter are the only people who actually leave useful reviews.

Corporate types want everyone to the the former. If they don't have a 4.5 star+ rating on a product or service, it is utter garbage because they are only concerned with marketing their junk by any means necessary. So they punish their workers and unsubtly tell users that they must rate 5 stars or they are assholes.

I use the whole rating system, because I am not leaving reviews for marketing wanks, I am leaving them for other readers so they can find the best stuff easily.

As a side note, a friend is a struggling author (is there any other kind?) and he has noted that high ratings are great, but it is the number of ratings that matters on places like Amazon. If you don't hit a certain threshold in reviews, your book will never make it onto suggested lists, and you will never be read. So if you like something mildly obscure, throw it a review on amazon, google, as many services as you can find. They need it. If it is a major release by an author with a publishing deal, fuck it they are fine.