Netflix is switching from a 5 star rating system to a simple thumbs up / down system.  The problem, they say, is that more people watch 3 star programs than 5 star.  This implies that star ratings don't reflect viewer enjoyment.

I say there's likely way more 3 star shows than 5 star, and the 5 stars are of such awesome quality you need to be in the mood for such heady goodness.  Often times, people just want something simple and breezy.